U.S. patent application number 12/169285 was filed with the patent office on 2010-01-14 for field replaceable units (frus) optimized for integrated metrology (im).
This patent application is currently assigned to Tokyo Electron Limited. Invention is credited to Shifang Li.
Application Number | 20100007875 12/169285 |
Document ID | / |
Family ID | 41504867 |
Filed Date | 2010-01-14 |
United States Patent
Application |
20100007875 |
Kind Code |
A1 |
Li; Shifang |
January 14, 2010 |
Field Replaceable Units (FRUs) Optimized for Integrated Metrology
(IM)
Abstract
An Integrated Metrology Sensor (IMS) including a plurality of
Field Replaceable Units (FRUs) for measuring a target on a wafer.
The FRU configurations can be optimized to include the appropriate
elements, so that each FRU can be pre-aligned and calibrated in the
factory to minimize the time need to swap the FRU in the field due
to failure or scheduled maintenance. The FRU configuration of the
IMS is optimized to shorten the time to repair a failure or perform
scheduled maintenance and increase the system reliability.
Inventors: |
Li; Shifang; (Pleasanton,
CA) |
Correspondence
Address: |
Tokyo Electron U.S. Holdings, Inc.
4350 West Chandler Blvd., Suite 10/11
Chandler
AZ
85226
US
|
Assignee: |
Tokyo Electron Limited
Tokyo
JP
|
Family ID: |
41504867 |
Appl. No.: |
12/169285 |
Filed: |
July 8, 2008 |
Current U.S.
Class: |
356/237.5 |
Current CPC
Class: |
G01B 11/27 20130101;
G01N 21/956 20130101; G01N 21/21 20130101; G01N 2021/213 20130101;
G03F 7/70633 20130101; G03F 7/70975 20130101; G01N 21/4788
20130101; G03F 7/70625 20130101 |
Class at
Publication: |
356/237.5 |
International
Class: |
G01N 21/88 20060101
G01N021/88 |
Claims
1. A Integrated Metrology Sensor (IMS) comprising: a compact
chassis assembly having a plurality of pre-aligned mounting devices
configured for mounting a plurality of calibrated Field Replaceable
Units (FRUs) at pre-determined locations, wherein the calibrated
FRUs are assembled, aligned, and calibrated to meet a set
characterization parameters; a calibrated wafer-positioning FRU
removably coupled to the compact chassis assembly and configured
for supporting and aligning a wafer; a calibrated high angle
focusing FRU configured to provide one or more pre-aligned
high-angle incident beams to a target on the wafer, the calibrated
high angle focusing FRU being removably coupled to the calibrated
wafer-positioning FRU and the compact chassis assembly; a
calibrated high angle collecting FRU configured to receive one or
more pre-aligned high-angle reflected beams from the target on the
wafer, the calibrated high angle focusing FRU being removably
coupled to the calibrated wafer-positioning FRU and the compact
chassis assembly; a calibrated source FRU removably coupled to the
compact chassis assembly and configured to provide at least one
pre-aligned high angle input beam to the calibrated high angle
focusing FRU; and a calibrated analyzer FRU removably coupled to
the compact chassis assembly and configured to receive at least one
pre-aligned high angle output beam.
2. The IMS as claimed in claim 1, further comprising: a calibrated
low angle focusing FRU configured to provide one or more
pre-aligned low-angle incident beams to the target on the wafer,
the calibrated low angle focusing FRU being removably coupled to
the calibrated wafer-positioning FRU and the compact chassis
assembly, wherein the calibrated source FRU is further configured
to provide at least one pre-aligned low angle input beam to the
calibrated low angle focusing FRU; and a calibrated low angle
collecting FRU configured to receive one or more pre-aligned
low-angle diffracted beams from the target on the wafer, the
calibrated low angle focusing FRU being removably coupled to the
calibrated wafer-positioning FRU and the compact chassis assembly,
wherein the calibrated analyzer FRU is further configured to
receive at least one pre-aligned low angle output beam.
3. The IMS as claimed in claim 1, wherein the calibrated
wafer-positioning FRU comprises a chamber, one or more optical
connection devices mounted in a wall of the chamber, a controller,
and one or more attachment elements configured for removably
coupling the calibrated wafer-positioning FRU to the compact
chassis assembly, each attachment element being configured to allow
the calibrated wafer-positioning FRU to be quickly and precisely
coupled to and/or decoupled from the compact chassis assembly.
4. The IMS as claimed in claim 3, wherein the calibrated
wafer-positioning FRU further comprises a platform subsystem
coupled to an interior wall of the chamber, a wafer-positioning
subsystem coupled to the platform subsystem, and a wafer alignment
sensor coupled to the wafer-positioning subsystem, wherein the
calibrated wafer-positioning FRU is further configured to support,
clamp, align, rotate, and/or translate the wafer.
5. The IMS as claimed in claim 4, wherein the calibrated
wafer-positioning FRU further comprises a translation port for
transferring the wafer into and/or out of the calibrated
wafer-positioning FRU.
6. The IMS as claimed in claim 1, wherein the calibrated high angle
focusing FRU comprises a chamber, one or more input optical
connection devices mounted in a first wall of the chamber, one or
more output optical windows mounted in a second wall of the
chamber, a controller, and one or more attachment elements
configured for removably coupling the calibrated high angle
focusing FRU to the compact chassis assembly, each attachment
element being configured to allow the calibrated high angle
focusing FRU to be quickly and precisely coupled to and/or
decoupled from the compact chassis assembly.
7. The IMS as claimed in claim 6, wherein the calibrated high angle
focusing FRU further comprises one or more polarizers and a set of
highly reflective curved surfaces configured for folding a light
path and for correcting aberrations.
8. The IMS as claimed in claim 1, wherein the calibrated high angle
collecting FRU comprises a chamber, one or more input optical
windows mounted in a first wall of the chamber, one or more output
optical connection devices mounted in a second wall of the chamber,
a controller, and one or more attachment elements configured for
removably coupling the calibrated high angle collecting FRU to the
compact chassis assembly, each attachment element being configured
to allow the calibrated high angle collecting FRU to be quickly and
precisely coupled to and/or decoupled from the compact chassis
assembly.
9. The IMS as claimed in claim 8, wherein the calibrated high angle
collecting FRU further comprises one or more polarizers and a set
of highly reflective curved surfaces configured for folding a light
path and for correcting aberrations.
10. The IMS as claimed in claim 2, wherein the calibrated low angle
focusing FRU comprises a chamber, one or more input optical
connection devices mounted in a first wall of the chamber, one or
more output optical windows mounted in a second wall of the
chamber, a controller, and one or more attachment elements
configured for removably coupling the calibrated low angle focusing
FRU to the compact chassis assembly, each attachment element being
configured to allow the calibrated low angle focusing FRU to be
quickly and precisely coupled to and/or decoupled from the compact
chassis assembly.
11. The IMS as claimed in claim 10, wherein the calibrated low
angle focusing FRU further comprises one or more polarizers and a
set of highly reflective curved surfaces configured for folding a
light path and for correcting aberrations.
12. The IMS as claimed in claim 2, wherein the calibrated low angle
collecting FRU comprises a chamber, one or more input optical
windows mounted in a first wall of the chamber, one or more output
optical connection devices mounted in a second wall of the chamber,
a controller, and one or more attachment elements configured for
removably coupling the calibrated low angle collecting FRU to the
compact chassis assembly, each attachment element being configured
to allow the calibrated low angle collecting FRU to be quickly and
precisely coupled to and/or decoupled from the compact chassis
assembly.
13. The IMS as claimed in claim 12, wherein the calibrated low
angle collecting FRU further comprises one or more polarizers and a
set of highly reflective curved surfaces configured for folding a
light path and for correcting aberrations.
14. The IMS as claimed in claim 1, further comprising: a first
calibrated beam reflection FRU configured to provide a pre-aligned
high angle input beam to the calibrated high angle focusing FRU,
wherein the first calibrated beam reflection FRU is removably
coupled to the calibrated high angle focusing FRU and the compact
chassis assembly; a first calibrated beam selector FRU removably
coupled to the first calibrated beam reflection FRU and the compact
chassis assembly; a calibrated beam generator FRU removably coupled
to the first calibrated beam selector FRU and the compact chassis
assembly; and a calibrated selector FRU removably coupled to the
calibrated beam generator FRU and the compact chassis assembly,
wherein the calibrated source FRU is coupled to the calibrated
selector FRU.
15. The IMS as claimed in claim 1, further comprising; a first
calibrated beam selector FRU configured to provide a first
calibrated input beam to a calibrated low angle focusing FRU,
wherein the first calibrated input beam includes one or more
calibrated low-angle incident beams, wherein the first calibrated
beam selector FRU is removably coupled to the calibrated low angle
focusing FRU and the compact chassis assembly; a calibrated beam
generator FRU removably coupled to the first calibrated beam
selector FRU and the compact chassis assembly; and a calibrated
selector FRU removably coupled to the calibrated beam generator FRU
and the compact chassis assembly, wherein the calibrated source FRU
is coupled to the calibrated selector FRU.
16. The IMS as claimed in claim 1, further comprising; a calibrated
second beam reflection FRU configured to receive a calibrated first
input beam from the calibrated high angle collecting FRU, wherein
the calibrated first input beam includes one or more high-angle
reflected beams wherein the calibrated second beam reflection FRU
is removably coupled to the calibrated high angle collecting FRU
and the compact chassis assembly; and a calibrated second beam
selector FRU removably coupled to the calibrated second beam
reflection FRU and the compact chassis assembly, wherein the
calibrated analyzer FRU is coupled to the calibrated second beam
selector FRU.
17. The IMS as claimed in claim 1, further comprising; a calibrated
second beam selector FRU configured to receive a calibrated first
input beam from a calibrated low angle collecting FRU, wherein the
calibrated first input beam includes one or more calibrated
low-angle reflected beams, the calibrated second beam selector FRU
being removably coupled to the calibrated low angle collecting FRU
and the compact chassis assembly, wherein the calibrated analyzer
FRU is coupled to the calibrated second beam selector FRU.
18. A method of operating an Integrated Metrology System (IMS)
comprising: mounting a plurality of calibrated Field Replaceable
Units (FRUs) using a plurality of pre-aligned mounting devices at
pre-determined locations on a compact chassis assembly wherein the
calibrated FRUs are assembled, aligned, and calibrated to meet a
set characterization parameters; positioning a wafer in a
calibrated wafer-positioning FRU removably coupled to the compact
chassis assembly and configured for supporting and aligning the
wafer; providing one or more pre-aligned high-angle incident beams
to a target on the wafer using a first set of calibrated FRUs, the
first set of calibrated FRUs being removably coupled to the compact
chassis assembly; receiving at least one pre-aligned high-angle
diffracted beam from the target on the wafer using a second set of
calibrated FRUs, the second set of calibrated FRUs being removably
coupled to the compact chassis assembly; performing a first
corrective action when a first error condition exists in one of the
first set of calibrated FRUs, or in one of the second set of
calibrated FRUs, or any combination thereof; and identifying the
target using the at least one pre-aligned high-angle diffracted
beam when the first error condition does not exist.
19. The method as claimed in claim 18, wherein the first corrective
action includes tuning one or more of the first set of calibrated
FRUs, aligning one or more of the first set of calibrated FRUs,
repairing one or more of the first set of calibrated FRUs, or
replacing one or more of the first set of calibrated FRUs with a
calibrated replacement FRU, or any combination thereof.
20. The method as claimed in claim 18 further comprising: providing
one or more pre-aligned low-angle incident beams to the target on
the wafer using a third set of calibrated FRUs, the third set of
calibrated FRUs being removably coupled to the compact chassis
assembly; receiving at least one pre-aligned low-angle diffracted
beam from the target on the wafer using a fourth set of calibrated
FRUs, the fourth set of calibrated FRUs being removably coupled to
the compact chassis assembly; performing a second corrective action
when a second error condition exists in one of the third set of
calibrated FRUs, or in one of the fourth set of calibrated FRUs, or
any combination thereof; and identifying the target using the at
least one pre-aligned low-angle diffracted beam when the second
error condition does not exist.
21. A method for creating a calibrated FRU for use in an Integrated
Metrology Sensor (IMS), the method comprising: selecting a first
set of initial components based on an expected replacement time for
the FRU when the FRU is initially designed; determining a required
replacement time during an initial design procedures, wherein the
first set of initial components are obtained, the FRU is assembled
using the first set of initial components, the assembled FRU is
calibrated, the calibrated FRU is installed, and time required for
these procedures is established; performing a query to determine if
the determined required replacement time is less than the expected
replacement time for the FRU; establishing the first set of initial
components as a potential design solution, when the required
replacement time is less than the expected replacement time; and
performing one or more corrective actions when the required
replacement time is not less than the expected replacement time.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to integrated optical
metrology, and more particularly to improving the integrated
optical metrology serviceability and availability by optimizing the
design of Field Replaceable Units (FRU) for the integrated optical
metrology system.
[0003] 2. Description of the Related Art
[0004] In the manufacturing of integrated circuits, very thin lines
or holes down to 45 nm or sometimes smaller are patterned into
photoresist and then transferred using an etching process into a
layer of material below on a silicon wafer. It is extremely
important to inspect and control the width and profile (also known
as critical dimensions or CDs) of these lines or holes.
Traditionally the inspection of CDs that are smaller than the
wavelength of visible light has been done using expensive and slow
scanning electron microscopes (CD-SEM) since all measurements are
done in vacuum. As the structures get smaller and smaller, the
process tolerance is getting tighter and tighter. Hence the
required measurement precision and accuracy also becomes tighter
and tighter. The measurement frequency and throughput also need to
increase in order to monitor the process condition in real time.
CD-SEM cannot meet the many CD metrology requirements in those
areas due to its low throughput and limited CD profiling
capability. In many cases, manufacturers need to measure CD and
profiles immediately after the photoresist has been patterned, a
non-destructive metrology is needed to avoid photoresist damage
induced by e-beam in CD-SEM. For real time process control or
advanced process control (APC), the measurement module needs to be
integrated with process equipment, such as wafer track that
develops the photoresist or etcher.
[0005] One measurement technique that has promise for
non-destructive and fast CD measurements is scatterometry.
Exemplary scatterometry techniques are described in U.S. Pat. No.
6,538,731, entitled "System and Method for Characterizing
Macro-Grating Test Patterns in Advanced Lithography and Etch
Processes", by Niu, et al., issued on Mar. 25, 2003, and is
incorporated in its entirety herein by reference. Exemplary
scatterometry techniques are described in U.S. Pat. No. 6,433,878,
, entitled "Method and Apparatus for the Determination of Mask
Rules Using Scatterometry", by Niu, et al., issued on April 13,
2002, and is incorporated in its entirety herein by reference. This
technique takes advantage of the fact that small periodic lines or
holes diffract an incident light beam, and the properties of the
light in each of the diffraction orders carries information of the
lines and holes. In practice, the optical properties of zero-th
diffraction order that is reflected (or, for transparent samples,
transmitted) from the periodic structures are measured with an
optical metrology sensor, and measured data is analyzed with an
analysis software, such as ODP. In performing scatterometry
measurement, the intensities of the reflected or transmitted beam
at various polarization states are measured versus wavelength, and
in some cases, versus angle of incidence of the beam.
[0006] Optical metrology sensor measures the optical properties of
the features on a wafer. These optical properties include the
intensity and polarization state of reflected beam. These
techniques are described in U.S. Pat. No. 7,064,829, entitled
"Generic Interface for an Optical Metrology System", by Li, et al.,
issued on Jun. 20, 2006, and are incorporated in its entirety
herein by reference. The optical metrology sensor can be designed
to sense one or more of this optical properties. For example, the
tool that measures the intensity of reflected beam is called a
reflectometer, and tools that measure the polarization change are
called ellipsometers. The optical metrology sensor typically uses
photometric or spectral photometric detectors.
[0007] An optical metrology sensor involves directing an incident
beam in one or more polarization states at a feature on a wafer,
measuring the resulting diffraction signals, and measuring the
signal from standard reflector in reflectometer case, the measured
signs are first analyzed to find the optical properties of the
feature, namely reflectivity or polarization state changes. The
measured optical properties of the feature are analyzed to
determine various characteristics of the feature. In semiconductor
manufacturing, optical metrology is typically used for quality
assurance, process control, and equipment control. For example,
after fabricating a periodic grating in proximity to a
semiconductor chip on a semiconductor wafer, an optical metrology
system is used to determine the profile of the periodic grating. By
determining the profile of the periodic grating, the quality of the
fabrication process utilized to form the periodic grating, and by
extension the semiconductor chip proximate the periodic grating,
can be evaluated. Further more, the measured dimensions of features
can be used to control the process equipment work conditions.
[0008] An integrated CD measurement tool must be both fast and
compact, and must be non-destructive to the wafer under test. The
wafer may also be loaded into the measurement tool at an arbitrary
angle creating further complications for instruments that have a
preferred measurement orientation with respect to certain wafer
features.
[0009] Integrated metrology tools are needed for real time process
control. The reliability and availability is paramount in this
scheme. Any problem in metrology module will hinder process control
and may cause process tool to stop. The maintenance time of the
integrated metrology modules also need to be significantly reduced
to minimize the downtime of the process tool and hence to maximize
the availability of the process tool.
SUMMARY OF THE INVENTION
[0010] The invention presents an integrated metrology system (IMS)
that is configured using a plurality of Field Replaceable Units
(FRUs). The invention presents an IMS that can be constructed and
used to measure CDs and overlay errors on periodic structures, and
the IMS is compact and well suited for integration into a wafer
process tool. The IMS has one or more FRUs that can be pre-aligned
and calibrated so that it can be swapped in field with
significantly reduced time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Embodiments of the invention will now be described, by way
of example only, with reference to the accompanying schematic
drawings in which corresponding reference symbols indicate
corresponding parts, and in which:
[0012] FIG. 1 depicts an exemplary optical metrology system in
accordance with embodiments of the invention;
[0013] FIG. 2 shows an exemplary block diagram of an optical
Integrated Metrology Sensor (IMS) including pre-aligned and/or
calibrated Field Replaceable Units (FRUs) in accordance with
embodiments of the invention;
[0014] FIG. 3 illustrates an exemplary flow diagram of a procedure
for using Field Replaceable Units (FRUs) in an optical Integrated
Metrology Sensor (IMS) in accordance with embodiments of the
invention;
[0015] FIG. 4 illustrates a simplified block diagram of a test
subsystem in accordance with embodiments of the invention; and
[0016] FIG. 5 illustrates an exemplary flow diagram of a procedure
for creating a calibrated FRU for use in an Integrated Metrology
Sensor (IMS) in accordance with embodiments of the invention.
DETAILED DESCRIPTION
[0017] Reliability, availability, and performance of semiconductor
equipment are critical in a modern fabrication environment. The
measured data from the integrated metrology system are used to
monitor and control the process step the wafer in that process
tool. A faulty in-line tool can cause throughput problems in the
associated production line.
[0018] The present invention provides an optical Integrated
Metrology Sensor (IMS) that uses Field Replaceable Units (FRUs) to
improve tool reliability and availability. The FRU concept can be
more easily applied when a new metrology tool is designed and
constructed. The entire metrology system can be separated into many
FRUs, and each one of the FRUs can be assembled, aligned,
calibrated, installed, and/or replaced with a minimum amount of
system level adjustment. In addition, there is a need to optimize
the separation strategy/plan when defining and/or isolating the FRU
from the entire IMS. It is noted that there is an optimized way to
define/divide each FRU from the whole system. If the FRU is defined
to be too large, the cost of replacing the FRU is high, and this
can increase the cost of ownership of the optical metrology sensor.
If the FRU is defined to be too small, it is more likely a system
level adjustment will be needed when the FRU is replaced, and this
can increase the cost of ownership of the optical metrology
sensor.
[0019] An improved integrated metrology (IM) tool can be designed
and built using varying sizes of FRUs. The inventor believes that
the use of FRUs in an IM system can significantly minimize and/or
substantially eliminate system level alignment, diagnostic and
calibration procedures that are presently required after a
scheduled maintenance is performed, and after fixing a system
failure.
[0020] FIG. 1 shows an exemplary block diagram of an optical
metrology system in accordance with embodiments of the invention.
In the illustrated embodiment, an Integrated Metrology Sensor (IMS)
100 can have a platform subsystem 103, a wafer-positioning
subsystem 102 and a wafer alignment sensor 104,
[0021] One or more optical outputs 106 from the lamp subsystem 105
can be transmitted to an illuminator subsystem 110. One or more
optical beams 111 can be sent from the illuminator subsystem 110 to
a selector subsystem 115. The selector subsystem 115 can provide
one or more optical beams 116 to a beam generator subsystem 120. In
addition, a reference subsystem 125 can provide one or more
reference beams to and/or exchange data with the beam generator
subsystem 120 using path 126.
[0022] The IMS 100 can comprise a first selectable reflection
subsystem 130 that can be used to direct one or more outputs 121
from the beam generator subsystem 120 as first outputs 131 when
operating in a first mode "HIGH" or as second outputs 132 when
operating in a second mode "LOW". When the first selectable
reflection subsystem 130 is operating in the first mode "HIGH", one
or more of the outputs 131 from the first selectable reflection
subsystem 130 can be directed to a first reflection subsystem 140,
and one or more outputs 141 from the first reflection subsystem 140
can be directed to a high angle focusing subsystem 145. When the
first selectable reflection subsystem 130 is operating in the
second mode "LOW", one or more of the second outputs 132 from the
first selectable reflection subsystem 130 can be directed to a low
angle focusing subsystem 135. Alternatively, other modes may be
used and other configurations may be used.
[0023] When the IMS 100 is operating in the first mode "HIGH", one
or more of the beams 97 from the high angle focusing subsystem 145
can be directed to the wafer 101. When the IMS 100 is operating in
the second mode "LOW", one or more of the beams 96 from the low
angle focusing subsystem 135 can be directed to the wafer 101.
Alternatively, other modes may be used and other configurations may
be used.
[0024] The IMS 100 can comprise a high angle collection subsystem
155, a low angle collection subsystem 165, a second reflection
subsystem 150, and a second selectable reflection subsystem
160.
[0025] When the IMS 100 is operating in the first mode "HIGH", one
or more of the beams 98 from the wafer 101 can be directed to the
high angle collection subsystem 155. In addition, the high angle
collection subsystem 155 can process the beams 98 obtained from the
wafer 101 and high angle collection subsystem 155 can provide
outputs 151 to the second reflection subsystem 150, and the second
reflection subsystem 150 can provide reflected outputs 152 to the
second selectable reflection subsystem 160. When the second
selectable reflection subsystem 160 is operating in the first mode
"HIGH", the reflected outputs 152 from the second reflection
subsystem 150 can be directed to the analyzer subsystem 170. For
example, one or more blocking elements can be moved allowing the
reflected outputs 152 from the second reflection subsystem 150 to
pass through without loss.
[0026] When the IMS 100 is operating in the second mode "LOW", one
or more of the beams 99 from the wafer 101 can be directed to the
low angle collection subsystem 165. In addition, the low angle
collection subsystem 165 can process the beams 99 obtained from the
wafer 101 and low angle collection subsystem 165 can provide
outputs 161 to the second selectable reflection subsystem 160. When
the second selectable reflection subsystem 160 is operating in the
second mode "LOW", the outputs 162 from the second selectable
reflection subsystem 160 can be directed to the analyzer subsystem
170.
[0027] When the IMS 100 is operating in the first mode "HIGH", high
incident angle data from the wafer 101 can be analyzed using the
analyzer subsystem 170, and when the IMS 100 is operating in the
second mode "LOW", low incident angle data from the wafer 101 can
be analyzed using the analyzer subsystem 170.
[0028] The IMS 100 can include one or more detection subsystems 175
that can receive inputs from the analyzer subsystem 170. One or
more of detection subsystems 175 can include one or more
spectrometers. For example, the spectrometers can operate from the
Deep-Ultra-Violet to the visible regions of the spectrum.
[0029] The IMS 100 can include one or more camera subsystems 180,
one or more illumination and imaging subsystems 185 coupled to one
or more of the camera subsystems 180. In addition, the IMS 100 can
also include one or more illuminator subsystems 184 that can be
coupled to one or more of the imaging subsystems 185.
[0030] In some embodiments, the IMS 100 can include one or more
auto-focusing subsystems 190 and auto-focusing beams 191.
[0031] One or more of the controllers (not shown) in one or more of
the subsystems (105, 110, 115, 120, 125, 130, 135, 140, 145, 150,
155, 160, 165, 170, 175, 180, 185 and 190) can be used when
performing real-time or non-real-time procedures. A controller can
receive real-time or non-real-time data to update subsystem,
processing element, process, recipe, profile, image, pattern,
and/or model data. One or more of the subsystems (105, 110, 115,
120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180,
185 and 190) can exchange data using one or more Semiconductor
Equipment Communications Standard (SECS) messages, can read and/or
remove information, can feed forward, and/or can feedback the
information, and/or can send information as a SECS message.
[0032] Those skilled in the art will recognize that one or more of
the subsystems (105, 110, 115, 120, 125, 130, 135, 140, 145, 150,
155, 160, 165, 170, 175, 180, 185, and 190) can include computers
and memory components (not shown) as required. For example, the
memory components (not shown) can be used for storing information
and instructions to be executed by computers (not shown) and may be
used for storing temporary variables or other intermediate
information during the execution of instructions by the various
computers/processors in the IMS 100. One or more of the subsystems
(105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165,
170, 175, 180, 185, and 190) can include the means for reading data
and/or instructions from a computer readable medium and can
comprise the means for writing data and/or instructions to a
computer readable medium. The IMS 100 can perform a portion of or
all of the processing steps of the invention in response to the
computers/processors in the processing system executing one or more
sequences of one or more instructions contained in a memory and/or
received using a computer-readable medium. Such instructions may be
received from another computer, a computer readable medium, or a
network connection. In addition, one or more of the subsystems
(105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165,
170, 175, 180, 185, and 190) can comprise control applications,
Graphical User Interface (GUI) components, and/or database
components. For example, the control applications can include
Advanced Process Control (APC) applications, Fault Detection and
Classification (FDC), and/or Run-to-Run (R2R) applications. In some
embodiments, APC applications, FDC applications, and/or R2R
applications can be performed using multi-angle metrology
procedures.
[0033] In some embodiments, the IMS 100 can include Optical Digital
Profilometry (ODP) elements (not shown), and ODP elements/systems
are available from Timbre Technologies, Inc. (a Tokyo Electron
Limited company). Alternatively, other data analysis elements for
the metrology systems may be used. For example, ODP techniques can
be used to obtain real-time data that can include critical
dimension (CD) data, gate structure data, thickness data, and the
wavelength ranges for the ODP data can range from less than
approximately 45 nm to greater than approximately 900 nm. Exemplary
ODP elements can include Optical Digital Profilometry Profiler
Library elements, Profiler Application Server (PAS) elements, and
other ODP Profiler Software elements. The ODP Profiler Library
elements can comprise application specific database elements of
optical spectra and its corresponding semiconductor profiles,
critical dimensions (CDs), and film thicknesses. The PAS elements
can comprise at least one computer that connects with optical
hardware and computer network. The PAS elements can be configured
to provide the data communication, ODP library operation, results
generation, results analysis, and results output. The ODP Profiler
Software elements can include the software installed on PAS
elements to manage measurement recipe, ODP Profiler library
elements, ODP Profiler data, ODP Profiler search/match results, ODP
Profiler calculation/analysis results, data communication, and PAS
interface to various metrology elements and computer network.
[0034] The IMS 100 can use polarizing reflectometry, spectroscopic
ellipsometry, spectroscopic reflectometry, or other optical
measurement techniques to accurately measure the profiles, CDs, and
film thickness of the features on the wafer. The integrated data
process (ODP) can be executed as an integrated data analyzer in an
integrated group of subsystems. In addition, the integrated group
(iODP) that consists of IMS 100 and data analyzer (ODP) into a
process tool eliminates the need to break the wafer for performing
the analyses or waiting for long periods for data from external
systems. iODP techniques can be integrated with TEL processing
systems and/or lithography systems and etch systems to provide
real-time process monitoring and control.
[0035] An exemplary ODP is described in U.S. Pat. No. 6,943,900,
entitled GENERATION OF A LIBRARY OF PERIODIC GRATING DIFFRACTION
SIGNAL, by Niu, et al., issued on Sep. 13, 2005, and is
incorporated in its entirety herein by reference.
[0036] Simulated diffraction signals with ODP can be generated by
applying Maxwell's equations and using a numerical analysis
technique to solve Maxwell's equations. For example, various
numerical analysis techniques, including variations of rigorous
coupled wave analysis (RCWA), can be used with multi-layer
structures. For a more detail description of RCWA, see U.S. Pat.
No. 6,891,626, titled CACHING OF INTRA-LAYER CALCULATIONS FOR RAPID
RIGOROUS COUPLED-WAVE ANALYSES, filed on Jan. 25, 2001, issued May
10, 2005, which is incorporated herein by reference in its
entirety.
[0037] An alternative procedure for generating a library of
simulated-diffraction signals can include using a machine learning
system (MLS). Prior to generating the library of
simulated-diffraction signals, the MLS is trained using known input
and output data. In one exemplary embodiment, simulated diffraction
signals can be generated using a MLS employing a machine learning
algorithm, such as back-propagation, radial basis function, support
vector, kernel regression, and the like. For a more detailed
description of machine learning systems and algorithms, see "U.S.
patent application Ser. No. 10/608,300, titled OPTICAL METROLOGY OF
STRUCTURES FORMED ON SEMICONDUCTOR WAFERS USING MACHINE LEARNING
SYSTEMS, filed on Jun. 27, 2003, which is incorporated herein by
reference in its entirety.
[0038] In various embodiments, one or more of the subsystems (105,
110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170,
175, 180, 185, and 190) can perform evaluation, inspection,
temperature control, alignment, verification, and/or storage on one
or more wafers. For example, wafer data that can include wafer
thickness, wafer curvature, layer thickness, wafer uniformity,
pattern data, damage data, or particle data, or any combination
thereof. In addition, controller 195 can determine if the wafer has
been processed correctly or if a rework is required.
[0039] The IMS 100 data can include measured, predicted, and/or
simulated data associated with patterns or structures, and the data
can be stored using processing, wafer, lot, recipe, site, or wafer
location data. the data can include variables associated with
patterned structure profile, metrology device type and associated
variables, and ranges used for the variables floated in the
modeling and values of variables that were fixed in the modeling.
The library data may include fixed and/or variable profile
parameters (such as CD, sidewall angle, refractive index (n) data
and extinction coefficient (k) data), and/or metrology device
parameters (such as wavelengths, angle of incidence, and/or azimuth
angle). For example, context and/or identification information such
as sensor ID, site ID, wafer ID, slot ID, lot ID, recipe, state,
and patterned structure ID may be used for organizing and indexing
data.
[0040] Controller 195 can include coupling means 196 that can be
used to couple the IMS 100 to other systems in a factory
environment. In some examples, controller 195 may be configured to
use factory level intervention and/or judgment rules to determine
which processes are monitored and which data can be used. In
addition, factory level intervention and/or judgment rules can be
used to determine how to manage the data when a process can be
changed, paused, and/or stopped. In addition, controller 195 can
provide configuration information and update information.
[0041] FIG. 2 shows an exemplary block diagram of an Integrated
Metrology Sensor (IMS) including Field Replaceable Units (FRUs) in
accordance with embodiments of the invention. In the illustrated
embodiment, a first configuration for the IMS 200 is shown.
Alternatively, a different configuration may be used, and a
different number of FRUs may be configured differently. Data and/or
messages can be sent from and/or received by the FRUs can be used
in the FRUs to optimize the process accuracy and precision. Data
can be passed to FRUs in real-time as real-time variable
parameters, overriding current recipe or model default values,
improving the alignment time for the tool, and improving the
measurement accuracy. FRUs can be used with a library-based system,
or regression-based system, or any combination thereof.
[0042] The IMS 200 can be used to examine and analyze a structure
formed on a wafer. Alternatively, other configurations may be used.
The illustrated IMS 200 can be used to determine the profile of a
target structure (not shown) formed on wafer 101. The target
structure can be formed in test areas on wafer 101, such as
adjacent to a device formed on wafer 101. In other embodiments,
target structure can be formed in an area of the device that does
not interfere with the operation of the device or along scribe
lines on wafer 101.
[0043] Reliability, availability, throughput, and performance are
important parameters for semiconductor equipments. Typically, most
of the optical metrology systems for thin-film and critical
dimension (CD) measurement are performed using stand-alone
equipment and off-line applications for process monitor. As the
semiconductor roadmap goes to smaller and smaller nodes, the
tightened tolerances provide additional challenges on semiconductor
process control. Integrated Metrology systems that are designed
using FRUs can be used to more accurately measure the smaller
structures created on the wafer, and can use the measured data
either to optimize the process tools used to make the wafer
structures, or for adjusting the process tool conditions for
further processing of the wafer. When integrated metrology tools
are incorporated into a manufacturing environment, the integrated
metrology tools must have an increased reliability, an increased
throughput, an increased availability, and a decreased repair
time.
[0044] FRUs can be used to improve tool reliability, to reduce the
time to repair, and to provide improved tool availability. FRUs can
easily be used when new equipment is designed. Many different IMSs
can be configured using FRUs that are configured differently. Each
one of the FRUs can be assembled, aligned, calibrated, and swapped
with a minimum amount of system level adjustment. To optimize cost
and minimize system level adjustments, the IMS can be constructed
using large, medium, and small FRUs.
[0045] Those skilled in the art will recognize that one or more of
the controllers (107, 117, 124, 134, 137, 144, 147, 154, 157, 164,
167, 174, 177, 184, 187, 194, 195, and 197) can include
microprocessors and memory components (not shown) as required. For
example, the memory components (not shown) can be used for storing
information and instructions to be executed by microprocessors (not
shown) and may be used for storing temporary variables or other
intermediate information during the execution of instructions by
the various computers/processors in the IMS 200. One or more of the
controllers (107, 117, 124, 134, 137, 144, 147, 154, 157, 164, 167,
174, 177, 184, 187, 194, 195, and 197) can include the means for
reading data and/or instructions from a computer readable medium
and can comprise the means for writing data and/or instructions to
a computer readable medium. The IMS 200 can perform a portion of or
all of the processing steps of the invention in response to the
computers/processors in the IMS 200 executing one or more sequences
of one or more instructions contained in a memory and/or received
using a computer-readable medium. Such instructions may be received
from another computer, a computer readable medium, or a network
connection.
[0046] One or more of the FRUs (205, 210, 215, 220, 225, 230, 235,
240, 245, 250, 255, 260, 265, 270, 275, 280, 285, and 290) can
comprise library components (not shown), Graphical User Interface
(GUI) components (not shown), and/or database components (not
shown). In addition, one or more of the FRUs (205, 210, 215, 220,
225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285,
and 290) can perform Advanced Process Control (APC) applications,
Fault Detection and Classification (FDC) applications, Run-to-Run
(R2R) applications, Double-Patterning (D-P) procedures, and/or
Double-Exposure (D-E) procedures.
[0047] When one or more of the FRUs (205, 210, 215, 220, 225, 230,
235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, and 290)
includes adjustable components, these components can be adjusted to
compensate for drift and/or system variations, to eliminate the
adjustment of the other FRUs, and to reduce the number of system
level alignments.
[0048] A compact chassis assembly 201 can be constructed that can
include pre-aligned mounting devices 202 for each of the FRUs (205,
210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270,
275, 280, 285, and 290) so that each FRU can be easily installed or
removed without removing the other FRUs. The pre-aligned mounting
devices 202 can be at pre-determined points and can be used to
align the FRUs and minimize the amount of system level testing when
an FRU is replaced.
[0049] When FRUs are created, the FRUs can be used in an IMS that
can be integrated with other processing tools. The IMS and the FRUs
are designed to be highly reliable, to have a reasonable cost, and
to be easily replaced to minimize the amount of tool downtime. FRUs
are designed to have short diagnostic times, short maintenance
times, and to minimize system level alignment times. In addition,
FRUs can be designed to be aligned, tested, calibrated, and stored
off-line for later use in a future scheduled maintenance
procedures, or to quickly fix a system failure without requiring a
system level alignment.
[0050] One or more of the FRUs can be designed and fabricated using
sealed chambers (closed units) and a vacuum environment can be
established within the sealed chamber, and optically transparent
windows can be provided in one or more of the chamber walls. For
example, one or more fused silica windows can be used.
Alternatively, other materials may be used. The sealed chambers can
be used to protect the wafer 101 from particles generated from the
moving optics, and to protect the optics from out-gassing from the
wafer 101.
[0051] When FRUs are used in the IMS 200, one or more of the
characterization parameters can be associated with each one of the
FRUs. The characterization parameters can be used to select the
components required for the FRUs, can be used to determine how to
assemble the selected components, and can be used to calibrate and
test the FRUs. The characterization parameters can include
generalized characterization parameters and FRU specific
characterization parameters. For example, the generalized
characterization parameters can include can include lifetime data,
repair data, replacement data, calibration data, preventive
maintenance data, actual operational data, required operational
data, dimensional data, historical data, or real-time data, or any
combination thereof associated with the components used in each
FRU.
[0052] One or more sets of characterization parameters can be
established when the FRU is constructed and/or repaired, and other
sets of characterization parameters can be used when the FRU is
calibrated and/or pre-aligned.
[0053] During and/or after some of the construction and/or repair
procedures, one or more of the characterization parameters
associated with an FRU can be used in calibration/pre-alignment
procedures to create a calibrated (pre-aligned) FRU. In some
embodiments, one or more of the calibration/pre-alignment
procedures can be performed while the FRU is configured within the
IMS 200. In other embodiments, the FRU is configured to be easily
removed from the IMS 200 and attached to the optical test bench
(410, FIG. 4) in an optical test subsystem (400, FIG.4) using
attachment elements.
[0054] During a maintenance procedure, one or more replacement FRUs
can be pre-aligned and/or calibrated before being installed in the
IMS 100, and new characterization parameters can be established for
each replacement FRU. A replacement FRU can be created when one or
more of the components in the FRU are replaced, repaired, and/or
realigned. The new characterization parameters can include new
lifetime data, new repair data, new replacement data, new
calibration data, new preventive maintenance data, new actual
operational data, new required operational data, new dimensional
data, new historical data, or new real-time data, or any
combination thereof associated with the components used in each
replacement FRU.
[0055] The wafer-positioning FRU 290 can include a
wafer-positioning chamber 291, one or more optical connection
devices (90, 91, 92, 93, 94, and 95) mounted in one or more walls
of the wafer-positioning chamber 291, a controller 197, and one or
more attachment elements 293 configured for coupling the
wafer-positioning FRU 290 to the compact chassis assembly 201. Each
optical connection devices (90, 91, 92, 93, 94, and 95) can operate
using one or more sets of wavelengths. For example, the optical
connection devices (90, 91, 92, 93, 94, and 95) can include optical
windows, optical fibers, and/or other devices.
[0056] A wafer-positioning FRU 290 can comprise a platform
subsystem 103, a wafer-positioning subsystem 102 coupled to the
platform subsystem 103, and a wafer alignment sensor 104 coupled to
the wafer-positioning subsystem 102. The wafer-positioning FRU 290
can be configured to support, clamp, align, and/or translate the
wafer 101. The wafer-positioning FRU 290 can include a translation
port 296 for transferring the wafer 101 into and/or out of the
wafer-positioning chamber 291.
[0057] In some embodiment, the wafer-positioning FRU 290 can
include X-Y stages to move the wafer 101. For example, a reduced
motion stage may be used with or without wafer stage .theta.
rotation, or a polar coordinate (R, .theta.) stage can be used to
reduce the footprint required by the IMS 200. A complete 360-degree
rotating range can be used, although a 180-degree range may be
acceptable in many cases. For example, one or more driver motors
(not shown) may be used.
[0058] When the source FRU 205 is installed in the IMS 200, the
source FRU 205 can provide one or more optical beams 111 to the
selector FRU 210. The source FRU 205 can include a chamber 206, one
or more output optical connection devices 207, and one or more
attachment elements 208 for coupling the FRU 205 to the compact
chassis assembly 201. In addition, the source FRU 205 can comprise
one or more lamp subsystems 105, one or more controllers 107, one
or more illuminator subsystems 110, and one or more optical outputs
106 from the lamp subsystem 105 can be transmitted internally to
the illuminator subsystem 110. Alternatively, additional subsystems
may be included.
[0059] The lamp subsystem 105 can include a high-pressure xenon
lamp 10 that can provide illumination between 220 nm and 1100 nm.
The lamp subsystem 105 can also include a deuterium lamp and
selection component 12 to provide deep-UV light between 190 nm and
340 nm. The shorter wavelength UV light can provide better results
on smaller structures. Alternatively, other white light sources may
be included. In some configurations, the lamp lifetime can be
typically .about.2000 hours.
[0060] A selection component 12 can include one or more reflecting
surfaces (not shown) that can be used to select between the two
light sources (10 and 11). In addition, the illuminator subsystems
110 can be used to turn-on and/or turn-off one or more of the beams
from the lamp subsystem 105. The illuminator subsystems 110 can be
used to protect the optics from excessive UV light and to allow the
measurement of a background signal. The illuminator subsystems 110
can create one or more optical beams 111 that are large enough to
illuminate one or more output optical connection devices 207 and
one or more multi-mode optical fibers 209. One or more of these
fibers 209 can have a core diameter of 100 microns.
[0061] In the existing stand-alone metrology systems, the optical
sources are designed as an integral part of the system, and the
entire metrology system can be off-line for an extended period of
time during maintenance. In addition, the new lamp must be
physically aligned to the system to compensate the lamp-to-lamp
variations. In some cases, the other components of the system also
need to be adjusted, and oftentimes a system re-calibration is
required. The existing procedures may take a day typically, and can
be much longer when some difficulty is encountered.
[0062] When a failure has occurred in a calibrated source FRU 205
in the IMS 200, the failed source FRU can be replaced by a
replacement source FRU that has been pre-calibrated and/or
pre-aligned. The characterization parameters associated with the
failed source FRU 205 or the replacement source FRU can include the
expected and/or actual lifetimes, the expected and/or actual
repair/replacement times, the expected and/or actual
calibration/measurement times, the expected and/or actual
wavelength data, the expected and/or actual intensity data, the
expected and/or actual beam width data, the expected and/or actual
temperature data for one or more of the light sources (10, 11) or
other components in the source FRU 205.
[0063] One or more of the controllers (107, 195) can be used for
storing characterization parameters and operational data for the
source FRU 205 and/or executing operational and calibration
procedures using the characterization parameters for the source FRU
205, and can be used to control the calibrated source FRU 205 when
the source FRU 205 is coupled in the IMS 200 or to an optical test
bench (410, FIG. 4) in an optical test subsystem (400, FIG.4). In
addition, the controller 107 can perform monitoring procedures that
can be used to provide warning data or failure data that can be
used to initiate a replacement procedure during operating or
calibrating procedures. When a new FRU is installed in the IMS 200
or when a new component is installed in the source FRU 205, the
controller (107, 195) can be programmed to compensate for the
system level variations, and a system level maintenance procedure
may not be required. For example, the lamp subsystems 105 and the
illuminator subsystems 110 can be adjusted to reduce or eliminate
the adjustment of the other components of the IMS 200 and the need
to re-calibrate the IMS 200.
[0064] When the source FRU 205 is being constructed and/or
repaired, the lamp subsystem 105, the illuminator subsystems 110
can be mounted and aligned within the chamber 206; the output
optical connection devices 207 can be mounted and aligned in one or
more of the chamber walls; and the chamber 206 can be evacuated and
sealed.
[0065] The source FRU 205 can be coupled to the selector FRU 210
using the optical connection devices (207 and 212a) and one or more
optical fibers 209. In other configurations, the source FRU 205 can
be coupled to the selector FRU 210 using one or more optically
transparent windows when the optical connection devices (207 and
212a) include optically transparent windows. For example, one or
more optical beams 111 can be sent from the illuminator subsystem
110 in the source FRU 205 to a selector subsystem 115 in the
selector FRU 210.
[0066] When the selector FRU 210 is installed in the IMS 200, the
selector FRU 210 can receive one or more input beams 116a from the
source FRU 205, can provide one or more output beams 116b to the
beam generator FRU 215. One or more of the beams (116a and 116b)
can include one or more reference beams and/or one or more
measurement beams. When pre-calibrated and/or pre-aligned FRUs
(205, 210) are used, pre-calibrated and/or pre-aligned beams (116a,
116b) can be established.
[0067] The selector FRU 210 can comprise a chamber 211, one or more
input optical connection devices 212a, one or more output optical
connection devices 212b, a controller 117, and one or more
attachment elements 213 for coupling the selector FRU 210 to the
compact chassis assembly 201. When the selector FRU 210 is being
constructed and/or repaired, the curved low-loss reflection
surfaces 115a can be mounted and aligned within the chamber 211;
the input optical connection devices 212a, and the output optical
connection devices 212b can be mounted and aligned in one or more
of the chamber walls; and the chamber 211 can be evacuated and
sealed.
[0068] When a failure has occurred in a calibrated selector FRU 210
in the IMS 200, the failed selector FRU 210 can be replaced by a
replacement selector FRU that has been pre-calibrated and/or
pre-aligned. The characterization parameters associated with the
failed and/or the replacement selector FRU 210 can include the
expected and/or actual lifetimes, the expected and/or actual
repair/replacement times, the expected and/or actual
calibration/measurement times, the expected and/or actual
wavelength data, the expected and/or actual intensity data, the
expected and/or actual beam width data, the expected and/or actual
temperature data, or the expected and/or actual loss data, or any
combination thereof for one or more of the curved low-loss
reflection surfaces 115a, the chamber 211, the input optical
connection devices 212a, and the output optical connection devices
212b or another component in the selector FRU 210.
[0069] One or more of the controllers (117, 195) can be used for
storing characterization parameters and operational data for the
selector FRU 210 and/or for executing operational and calibration
procedures using the characterization parameters for the selector
FRU 210. The controllers (117, 195) can also be used to control the
calibrated selector FRU 210 when the selector FRU 210 is coupled in
the IMS 200 or to an optical test bench (410, FIG. 4) in an optical
test subsystem (400, FIG.4). In addition, the controller 117 can
perform monitoring procedures that can be used to provide warning
data or failure data that can be used to initiate a replacement
procedure during operating or calibrating procedures. When a new
FRU is installed in the IMS 200 or when a new component is
installed in the selector FRU 210, the controllers (117, 195) can
be programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, the lamp subsystems 105, the illuminator subsystems 110,
or the curved low-loss reflection surfaces 115a can be adjusted to
reduce or eliminate the adjustment of the other components of the
IMS 200 and the need to re-calibrate the IMS 200.
[0070] The selector FRU 210 can be coupled to the beam generator
FRU 215 using the optical connection devices (212b and 217a) and
one or more optical fibers 214. In other configurations, the
selector FRU 210 can be coupled to the beam generator FRU 215 using
one or more optically transparent windows when the optical
connection devices (212b and 217a) include optically transparent
windows.
[0071] When the beam generator FRU 215 is installed in the IMS 200,
the beam generator FRU 215 can receive one or more input beams 121a
from the selector FRU 210, can provide one or more output beams
121b to the first beam selector FRU 220. One or more of the beams
(121a and 121b) can include one or more reference beams and/or one
or more measurement beams. When pre-calibrated and/or pre-aligned
FRUs (210, 215) are used, pre-calibrated and/or pre-aligned beams
(121a, 121b) can be established.
[0072] The beam generator FRU 215 can comprise a chamber 216, one
or more input optical connection devices 217a, one or more output
optical connection devices 217b, a controller 124, and one or more
attachment elements 218 for coupling the beam generator FRU 215 to
the compact chassis assembly 201. In addition, the beam generator
FRU 215 can comprise one or more beam generator subsystems 120 and
one or more reference subsystems 125. Alternatively, additional
subsystems may be included. One or more of the reference subsystems
125 can provide one or more reference beams to and/or exchange data
with the beam generator subsystem 120 using path 126. For example,
the beam generator subsystems 120, the reference subsystems 125, or
the controller 124 can perform measurement functions so that the
beam generator FRU 215 can be pre-aligned before it is installed in
the IMS 200 during a shortened maintenance cycle.
[0073] When the beam generator FRU 215 is being constructed and/or
repaired, the beam generator subsystem 120, the reference subsystem
125, can be aligned and mounted within the chamber 211; the input
optical connection devices 217a, and the output optical connection
devices 217b can be aligned and mounted in one or more of the walls
of the chamber 211; and the chamber 211 can be evacuated and
sealed.
[0074] When a failure has occurred in a calibrated beam generator
FRU 215 in the IMS 200, the failed beam generator FRU 215 can be
replaced by a replacement beam generator FRU that has been
pre-calibrated and/or pre-aligned. The characterization parameters
associated with the failed and/or replacement beam generator FRU
215 can include the expected and/or actual lifetimes, the expected
and/or actual repair/replacement times, the expected and/or actual
calibration/measurement times, the expected and/or actual
wavelength data, the expected and/or actual intensity data, the
expected and/or actual beam width data, the expected and/or actual
temperature data, or the expected and/or actual loss data, or any
combination thereof for the beam generator subsystem 120, the
reference subsystem 125, the chamber 216, the input optical
connection devices 217a, and the output optical connection devices
217b, the optical fiber 214, or other components in the beam
generator FRU 215.
[0075] One or more of the controllers (124, 195) can be used for
storing characterization parameters and operational data for the
beam generator FRU 215 and/or for executing operational and
calibration procedures using the characterization parameters for
the beam generator FRU 215. The controllers (124, 195) can also be
used to control the calibrated beam generator FRU 215 when the beam
generator FRU 215 is coupled in the IMS 200 or to an optical test
bench (410, FIG. 4) in an optical test subsystem (400, FIG.4). In
addition, the controller 124 can perform monitoring procedures that
can be used to provide warning data or failure data that can be
used to initiate a replacement procedure during operating or
calibrating procedures. When a new FRU is installed in the IMS 200
or when a new component is installed in the beam generator FRU 215,
the controllers (124, 195) can be programmed to compensate for the
system level variations, and a system level maintenance procedure
may not be required. For example, the beam generator subsystem 120,
or the reference subsystem 125 can be adjusted to reduce or
eliminate the adjustment of the other components of the IMS 200 and
the need to re-calibrate the IMS 200.
[0076] The beam generator FRU 215 can be coupled to the first beam
selector FRU 220 using the optical connection devices (217b and
222a) and one or more optical fibers 219. In other embodiments, the
beam generator FRU 215 can be coupled to the first beam selector
FRU 220 using one or more optically transparent windows when the
optical connection devices (217b and 222a) include optically
transparent windows. For example, one or more optical beams 121 b
can be sent from one or more beam generator FRU 215 to one or more
of the first beam selector FRUs 220.
[0077] When the first beam selector FRU 220 is operating in the IMS
200, the first beam selector FRU 220 can receive one or more first
input beams 131a from the beam generator FRU 215, can provide one
or more first output beams 132a to the first beam reflection FRU
220 during a first mode, and can provide one or more low angle
reflected beams 133a to the low angle focusing FRU 225 during a
second mode. When pre-calibrated and/or pre-aligned FRUs (215, 220)
are used, pre-calibrated and/or pre-aligned beams (131a, 132a,
133a) can be established.
[0078] The first beam selector FRU 220 can comprise a chamber 221,
one or more input optical connection devices 222a, one or more
first output optical connection devices 222b, one or more second
output optical connection devices 222c, a controller 134, and one
or more attachment elements 223 for coupling the first beam
selector FRU 220 to the compact chassis assembly 201. The first
beam selector FRU 220 can comprise one or more first low-loss
reflecting surfaces 130a that can be used to allow the first input
beam 131a to pass through to the first output optical connection
devices 222b when the IMS 200 is operating in the first mode (HIGH)
and that can be used to direct the first input beam 131a to the
second output optical connection devices 222c when the IMS 200 is
operating in the second mode (LOW). One or more of the first
low-loss reflecting surfaces 130a can be a first surface convex
mirror, or a concave fused silica mirror. The first low-loss
reflecting surfaces 130a can be used to correct the aberrations so
that the low angle reflected beam 133a has near diffraction-limited
quality from 190 nm to 1100 nm. For example, one or more of the
first low-loss reflecting surfaces 130a can be moved to a first
position when the IMS 200 is operating in the first mode (LOW), and
one or more of the first low-loss reflecting surfaces 130a can be
moved to a second position when the IMS 200 is operating in the
second mode (HIGH). In addition, additional components (not shown)
can be included that can perform sensing, positioning, reflecting,
summing, and/or focusing functions as required.
[0079] When the first beam selector FRU 220 is being constructed
and/or repaired, the first low-loss reflecting surfaces 130a can be
aligned and mounted within the chamber 221; the input optical
connection devices 222a, the first output optical connection
devices 222b and the second output optical connection devices 222c
can be aligned and mounted in one or more walls of the chamber 221;
and the chamber 226 can be evacuated and sealed.
[0080] When a failure has occurred in a calibrated first beam
selector FRU 220 in the IMS 200, the failed first beam selector FRU
220 can be replaced by a replacement first beam selector FRU that
has been pre-calibrated and/or pre-aligned. The characterization
parameters associated with the failed and/or replacement first beam
selector FRU 220 can include the expected and/or actual lifetimes,
the expected and/or actual repair/replacement times, the expected
and/or actual calibration/measurement times, the expected and/or
actual wavelength data, the expected and/or actual intensity data,
the expected and/or actual beam width data, the expected and/or
actual temperature data, or the expected and/or actual loss data,
or any combination thereof for the first low-loss reflecting
surfaces 130a, the chamber 221, the input optical connection
devices 222a, and the output optical connection devices (222b and
222c), the optical fiber 219, or other components in the first beam
selector FRU 220.
[0081] One or more of the controllers (134, 195) can be used for
storing characterization parameters and operational data for the
first beam selector FRU 220 and/or for executing operational and
calibration procedures using the characterization parameters for
the first beam selector FRU 220. The controllers (134, 195) can
also be used to control the calibrated first beam selector FRU 220
when the first beam selector FRU 220 is coupled in the IMS 200 or
to an optical test bench (410, FIG. 4) in an optical test subsystem
(400, FIG.4). In addition, the controller 134 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the first beam selector FRU 220, the controllers (134, 195) can be
programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, the first low-loss reflecting surfaces 130a, the chamber
221, the input optical connection devices 222a, the output optical
connection devices (222b and 222c), or the optical fiber 219 can be
adjusted to reduce or eliminate the adjustment of the other
components of the IMS 200 and the need to re-calibrate the IMS
200.
[0082] The first beam selector FRU 220 can be coupled to the first
beam reflection FRU 230 using the optical connection devices (222b
and 232a) and one or more optical fibers 224a. In other
embodiments, the first beam selector FRU 220 can be coupled to the
first beam reflection FRU 230 using one or more optically
transparent windows when the optical connection devices (222b and
232a) include optically transparent windows. In addition, the first
beam selector FRU 220 can be coupled to the low angle focusing FRU
225 using the optical connection devices (222c and 227a) and one or
more optical fibers 224b. In other embodiments, the first beam
selector FRU 220 can be coupled to the low angle focusing FRU 225
using one or more optically transparent windows when the optical
connection devices (222b and 227a) include optically transparent
windows.
[0083] When a low angle focusing FRU 225 is installed in the IMS
200, the low angle focusing FRU 225 can receive one or more low
angle input beams 135a from the first beam selector FRU 220 and can
provide a low angle focused beam 135b to the wafer-positioning FRU
290. When pre-calibrated and/or pre-aligned FRUs (220, 225) are
used, pre-calibrated and/or pre-aligned beams (135a, 135b) can be
established.
[0084] The low angle focusing FRU 225 can comprise a chamber 226,
one or more input optical connection devices 227a, one or more
output optical connection devices 227b, one or more attachment
elements 228 for coupling the low angle focusing FRU 225 to one or
more walls of the wafer-positioning chamber 291, and a controller
137.
[0085] The low angle focusing FRU 225 can also include one or more
polarizers 136 that can linearly polarize the light before the
light is incident onto the wafer 101, and the polarization can be
selected to maximize the sensitivity of the optical measurement to
the parameters of the sample. In some examples, one or more of the
polarizers 136 can provide the S-polarized light onto the wafer
101. In other examples, a polarizer 136 may be rotated when
collecting additional measurement data. In addition, a first set of
highly reflective curved surfaces (138 and 139) can be used to fold
the light path so that the non-normal incidence angles do not lead
to unnecessarily large footprint for the first beam selector FRU
220. The smaller footprint allows the first beam selector FRU 220
to be used in a compact IMS 200. One or more of the highly
reflective curved surfaces (138 and 139) can be a first surface
convex mirror, or a concave fused silica mirror. In addition, the
two highly reflective curved surfaces (138 and 139) can be used to
correct the aberrations so that the low angle focused beam 135b has
near diffraction-limited quality from 190 nm to 1100 nm. In
addition, additional components (not shown) can be included that
can perform positioning, measuring, reflecting, summing, and/or
focusing functions as required.
[0086] For example, the light sent to the wafer can be focused and
imaged by the first set of highly reflective curved surfaces (138
and 139). In addition, the polarizer 136 may be configured to have
beam-splitting properties and can be made from alpha barium borate.
For example, a beam may be split into S-polarized light, and
P-polarized light. Some of the optical fibers used in the IMS 200
can have smaller core diameters than other fibers so that the
measurements are not overly sensitive to focus. In various
configurations, the diameter of optical fibers or optical windows
can be used to determine the geometric size of the measurement spot
on the wafer 101.
[0087] When the low angle focusing FRU 225 is being constructed
and/or repaired, the polarizers 136, and the first set of highly
reflective curved surfaces (138 and 139) can be aligned and mounted
within the chamber 226; the input optical connection devices 227a
and the output optical connection devices 227b can be mounted in
one or more of the walls of the chamber 226; and the chamber 226
can be evacuated and sealed.
[0088] When a failure has occurred in a calibrated low angle
focusing FRU 225 in the IMS 200, the failed low angle focusing FRU
can be replaced by a replacement low angle focusing FRU that has
been pre-calibrated and/or pre-aligned. The characterization
parameters associated with the failed and/or replacement first low
angle focusing FRU 225 can include the expected and/or actual
lifetimes, the expected and/or actual repair/replacement times, the
expected and/or actual calibration/measurement times, the expected
and/or actual wavelength data, the expected and/or actual intensity
data, the expected and/or actual beam width data, the expected
and/or actual temperature data, the expected and/or actual
adjustment ranges, the expected and/or actual polarization values,
or the expected and/or actual loss data, or any combination thereof
for the polarizers 136, the first set of highly reflective curved
surfaces (138 and 139), the chamber 226, the input optical
connection devices 227a, and the output optical connection devices
227b, the optical fiber 224b, or other components in the low angle
focusing FRU 225.
[0089] One or more of the controllers (137, 195) can be used for
storing characterization parameters and operational data for the
low angle focusing FRU 225 and/or for executing operational and
calibration procedures using the characterization parameters for
the low angle focusing FRU 225. The controllers (137, 195) can also
be used to control the calibrated low angle focusing FRU 225 when
the low angle focusing FRU 225 is coupled in the IMS 200 or to an
optical test bench (410, FIG. 4) in an optical test subsystem (400,
FIG.4). In addition, the controller 137 can perform monitoring
procedures that can be used to provide warning data or failure data
that can be used to initiate a replacement procedure during
operating or calibrating procedures. When a new FRU is installed in
the IMS 200 or when a new component is installed in the low angle
focusing FRU 225, the controllers (137, 195) can be programmed to
compensate for the system level variations, and a system level
maintenance procedure may not be required. For example, the
polarizers 136, the first set of highly reflective curved surfaces
(138 and 139), the chamber 226, the input optical connection
devices 227a, the output optical connection devices 227b, and the
optical fiber 224b can be adjusted to reduce or eliminate the
adjustment of the other components of the IMS 200 and the need to
re-calibrate the IMS 200.
[0090] The low angle focusing FRU 225 can be coupled to the
wafer-positioning FRU 290 using the optically transparent windows.
In other embodiments, the low angle focusing FRU 225 can be coupled
to the wafer-positioning FRU 290 using one or more optical fibers.
For example, one or more low angle focused beams 135b can be sent
from the low angle focusing FRU 225 as a low angle incident beam 96
to a measurement spot on a wafer in the wafer-positioning FRU 290
when the IMS 200 is operating in a second mode (LOW). In addition,
the low angle incident beam 96 can have an angle of incidence that
can between approximately 45 degrees and approximately 80 degrees
from a normal vector perpendicular to a wafer surface.
Alternatively, the low angle focusing FRU 225 can include one or
more movable mirrors.
[0091] When a first beam reflection FRU 230 is installed in the IMS
200, the first beam reflection FRU 230 can receive one or more
input beams 141a from the first beam selector FRU 220 and can
provide one or more high angle reflected beam 141b to the high
angle focusing FRU 235. Alternatively, additional subsystems may be
included. One or more of the beams (141a and 141b) can include one
or more reference beams and/or one or more measurement beams. When
pre-calibrated and/or pre-aligned FRUs (220, 230) are used,
pre-calibrated and/or pre-aligned beams (141a, 141b) can be
established.
[0092] The first beam reflection FRU 230 can comprise a chamber
231, one or more input optical connection devices 232a mounted in a
wall of the chamber 231, one or more output optical connection
devices 232b mounted in a wall of the chamber 221, a controller
144, and one or more attachment elements 233 for coupling the first
beam reflection FRU 230 to the compact chassis assembly 201.
[0093] The first beam reflection FRU 230 can also comprise one or
more second low-loss reflecting surfaces 140a that can be used to
allow the input beam 141a to pass through to the output optical
connection devices 232b when the metrology system is operating in
the first mode (HIGH). One or more of the second low-loss
reflecting surfaces 140a can be a first surface convex mirror, or a
concave mirror. The second low-loss reflecting surfaces 140a can be
used to correct aberrations so that the high angle reflected beam
141b has near diffraction-limited quality from 190 nm to 1100 nm.
In addition, additional components (not shown) can be included that
can perform reflecting, summing, and/or focusing functions as
required.
[0094] When the first beam reflection FRU 230 is being constructed
and/or repaired, the second low-loss reflecting surfaces 140a can
be aligned and mounted within the chamber 231; the input optical
connection devices 232a and the output optical connection devices
232b can be mounted in one or more of the walls of the chamber 231;
and the chamber 231 can be evacuated and sealed.
[0095] When a failure has occurred in a calibrated first beam
reflection FRU 230 in the IMS 200, the failed first beam reflection
FRU can be replaced by a replacement first beam reflection FRU that
has been pre-calibrated and/or pre-aligned. The characterization
parameters associated with the failed and/or replacement first beam
reflection FRU 230 can include the expected and/or actual
lifetimes, the expected and/or actual repair/replacement times, the
expected and/or actual calibration/measurement times, the expected
and/or actual wavelength data, the expected and/or actual intensity
data, the expected and/or actual beam width data, the expected
and/or actual temperature data, the expected and/or actual
adjustment ranges, the expected and/or actual polarization values,
or the expected and/or actual loss data, or any combination thereof
for the second low-loss reflecting surfaces 140a, the chamber 231,
the input optical connection devices 232a, and the output optical
connection devices 232b, the optical fiber 224a, or other
components in the first beam reflection FRU 230.
[0096] One or more of the controllers (144, 195) can be used for
storing characterization parameters and operational data for the
first beam reflection FRU 230 and/or for executing operational and
calibration procedures using the characterization parameters for
the first beam reflection FRU 230. The controllers (144, 195) can
also be used to control the calibrated first beam reflection FRU
230 when the first beam reflection FRU 230 is coupled in the IMS
200 or to an optical test bench (410, FIG. 4) in an optical test
subsystem (400, FIG.4). In addition, the controller 144 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the first beam reflection FRU 230, the controllers (144, 195) can
be programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, second low-loss reflecting surfaces 140a, the chamber 231,
the input optical connection devices 232a, the output optical
connection devices 232b, and the optical fiber 224a can be adjusted
to reduce or eliminate the adjustment of the other components of
the IMS 200 and the need to re-calibrate the IMS 200.
[0097] The first beam reflection FRU 230 can be coupled to the high
angle focusing FRU 235 using the optical connection devices (232b
and 237a) and one or more optical fibers 234. In other embodiments,
the first beam reflection FRU 230 can be coupled to the high angle
focusing FRU 235 using one or more optically transparent windows
when the optical connection devices (232b and 237a) include
optically transparent windows. For example, one or more high angle
reflected beams 141 b can be sent from the first beam reflection
FRU 230 to the high angle focusing FRU 235 when the IMS 200 is
operating in a first mode (HIGH).
[0098] When the high angle focusing FRU 235 is installed in the IMS
200, the high angle focusing FRU 235 can receive one or more high
angle input beams 145a from the first beam reflection FRU 230 and
can provide one high angle focused beams 145b to the
wafer-positioning FRU 290. When pre-calibrated and/or pre-aligned
FRUs (220, 225) are used, pre-calibrated and/or pre-aligned beams
(135a, 135b) can be established.
[0099] The high angle focusing FRU 235 can comprise a chamber 236,
one or more input optical connection devices 237a, one or more
output optical windows 237b, one or more attachment elements 238
for coupling the high angle focusing FRU 235 to one or more walls
of the wafer-positioning chamber 291, and a controller 147. The
high angle focusing FRU 235 can also include one or more polarizers
146 that can linearly polarize the light before the beam is
incident onto the wafer 101, and the polarization can be selected
to maximize the sensitivity of the optical measurement to the
parameters of the sample. In some examples, one or more of the
polarizers 146 can provide the S-polarized light onto the wafer
101. In other examples, a polarizer 146 may be rotated to collect
additional measurement data. In addition, a second set of highly
reflective curved surfaces (148 and 149) can be used to fold the
light path so that the non-normal incidence angles do not lead to
unnecessarily large footprint for the high angle focusing FRU 235.
A small footprint is desirable so that the high angle focusing FRU
235 can be used in a compact IMS 200. One or more of the reflecting
surfaces can be a first surface convex mirror, or a concave fused
silica mirror. The second set of highly reflective curved surfaces
(148 and 149) can be used to correct aberrations so that the high
angle focused beam 145b has near diffraction-limited quality from
190 nm to 1100 nm. In addition, additional components (not shown)
can be included that can perform positioning, reflecting, summing,
and/or focusing functions as required.
[0100] In some configurations, the light beam can be focused and
imaged by the second set of highly reflective curved surfaces (148
and 149) before being sent to the wafer. In addition, the polarizer
146 may be configured to have beam-splitting properties and can be
made from alpha barium borate. For example, a beam may be split
into S-polarized light, and P-polarized light. Some of the optical
fibers used in the IMS 200 can have smaller core diameters than
other fibers so that the measurements are not overly sensitive to
focus. In various configurations, the diameter of optical fibers or
optical windows can be used to determine the geometric size of the
measurement spot on the wafer 101.
[0101] When the high angle focusing FRU 235 is constructed and/or
repaired, the polarizers 146 and the second set of highly
reflective curved surfaces (148 and 149) can be mounted within the
chamber 236; the input optical connection devices 237a and the
output optical windows 237b can be mounted in one or more of the
chamber walls; and the chamber 236 can be evacuated and sealed.
[0102] When a failure has occurred in a calibrated high angle
focusing FRU 235 in the IMS 200, the failed high angle focusing FRU
can be replaced by a replacement high angle focusing FRU that has
been pre-calibrated and/or pre-aligned. The characterization
parameters associated with the failed and/or replacement high angle
focusing FRU 235 can include the expected and/or actual lifetimes,
the expected and/or actual repair/replacement times, the expected
and/or actual calibration/measurement times, the expected and/or
actual wavelength data, the expected and/or actual intensity data,
the expected and/or actual beam width data, the expected and/or
actual temperature data, the expected and/or actual adjustment
ranges, the expected and/or actual polarization values, or the
expected and/or actual loss data, or any combination thereof for
the polarizers 146 and the second set of highly reflective curved
surfaces (148 and 149), the chamber 236, the input optical
connection devices 237a, and the output optical connection devices
237b, the optical fiber 234, or other components in the high angle
focusing FRU 235.
[0103] One or more of the controllers (147, 195) can be used for
storing characterization parameters and operational data for the
high angle focusing FRU 235 and/or for executing operational and
calibration procedures using the characterization parameters for
the high angle focusing FRU 235. The controllers (147, 195) can
also be used to control the calibrated high angle focusing FRU 235
when the high angle focusing FRU 235 is coupled in the IMS 200 or
to an optical test bench (410, FIG. 4) in an optical test subsystem
(400, FIG.4). In addition, the controller 147 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the high angle focusing FRU 235, the controllers (147, 195) can be
programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, the polarizers 146 and the second set of highly reflective
curved surfaces (148 and 149), the chamber 236, the input optical
connection devices 237a, and the output optical connection devices
237b, the optical fiber 234 can be adjusted to reduce or eliminate
the adjustment of the other components of the IMS 200 and the need
to re-calibrate the IMS 200.
[0104] The high angle focusing FRU 235 can be coupled to the
wafer-positioning FRU 290 using the optically transparent windows.
In other embodiments, the high angle focusing FRU 235 can be
coupled to the wafer-positioning FRU 290 using one or more optical
fibers. For example, one or more high angle focused beams 145b can
be sent from the high angle focusing FRU 235 as a high angle
incident beam 97 to a measurement spot on a wafer in the
wafer-positioning FRU 290 when the IMS 200 is operating in a first
mode (HIGH). In addition, high angle incident beam 97 can have an
angle of incidence that can be between approximately 15 degrees and
approximately 50 degrees for a normal vector perpendicular to the
wafer surface. Alternatively, the high angle focusing FRU 235 can
include one or more movable mirrors.
[0105] When the high angle collecting FRU 240 is installed in the
IMS 200, the high angle collecting FRU 240 can receive one or more
input beams 155a from the wafer-positioning FRU 290 and can provide
one high angle output beams 155b to the second beam reflection FRU
245. The high angle collecting FRU 240 can comprise a chamber 241,
one or more input optical connection devices 242a, one or more
output optical connection devices 242b, one or more attachment
elements 238 for coupling the high angle collecting FRU 240 to one
or more walls of the wafer-positioning chamber 291, and a
controller 157. When pre-calibrated and/or pre-aligned FRUs (290,
240) are used, pre-calibrated and/or pre-aligned beams (155a, 155b)
can be established.
[0106] The high angle collecting FRU 240 can include one or more
polarizers 156 that can linearly polarize the light after the beam
is reflected from the wafer 101, and the polarization can be
selected to maximize the sensitivity of the optical measurement to
the parameters of the sample. In some examples, one or more of the
polarizers 156 can provide the S-polarized light. In other
examples, a polarizer 156 may be rotated to collect additional
measurement data. In addition, a third set of highly reflective
curved surfaces (158 and 159) can be used to fold the light path so
that the non-normal incidence angles do not lead to unnecessarily
large footprint for the high angle collecting FRU 240. A small
footprint allows the high angle collecting FRU 240 to be used in a
compact IMS 200. One or more of the reflecting surfaces can be a
first surface convex mirror, or a concave fused silica mirror. The
third set of highly reflective curved surfaces (158 and 159) can be
used to correct aberrations so that the high angle output beam 155b
has near diffraction-limited quality from 190 nm to 1100 nm. In
addition, additional components (not shown) can be included that
can perform positioning, reflecting, summing, and/or focusing
functions as required.
[0107] In some embodiments, the high angle collecting FRU 240 can
receive one or more high-angle diffracted beams 98 from the wafer
surface as a high-angle input beam 155a. The light sent from the
wafer (high-angle input beam 155a) can be collected and imaged by
the third set of highly reflective curved surfaces (158 and 159).
In addition, the polarizer 156 may be configured to have
beam-splitting properties and can be made from alpha barium borate.
For example, a beam may be split into S-polarized light, and
P-polarized light. Some of the optical fibers used in the metrology
system can have smaller core diameters than other fibers so that
the measurements are not overly sensitive to focus. In various
configurations, the diameter of optical fibers or optical windows
can be used to determine the geometric size of the measurement spot
on the wafer 101.
[0108] When the high angle collecting FRU 240 is being constructed
and/or repaired, the polarizers 156 and the third set of highly
reflective curved surfaces (158 and 159) can be aligned and mounted
within the chamber 241; the input optical connection devices 242a
and the output optical connection devices 242b can be mounted in
one or more of the chamber walls; and the chamber 241 can be
evacuated and sealed.
[0109] When a failure has occurred in a calibrated high angle
collecting FRU 240 in the IMS 200, the failed high angle collecting
FRU can be replaced by a replacement high angle collecting FRU that
has been pre-calibrated and/or pre-aligned. The characterization
parameters associated with the failed and/or replacement high angle
collecting FRU 240 can include the expected and/or actual
lifetimes, the expected and/or actual repair/replacement times, the
expected and/or actual calibration/measurement times, the expected
and/or actual wavelength data, the expected and/or actual intensity
data, the expected and/or actual beam width data, the expected
and/or actual temperature data, the expected and/or actual
adjustment ranges, the expected and/or actual polarization values,
or the expected and/or actual loss data, or any combination thereof
for the polarizers 156 and the third set of highly reflective
curved surfaces (158 and 159), the chamber 241, the input optical
connection devices 242a, and the output optical connection devices
242b, or other components in the high angle collecting FRU 240.
[0110] One or more of the controllers (157, 195) can be used for
storing characterization parameters and operational data for the
high angle collecting FRU 240 and/or for executing operational and
calibration procedures using the characterization parameters for
the high angle collecting FRU 240. The controllers (157, 195) can
also be used to control the calibrated high angle collecting FRU
240 when the high angle collecting FRU 240 is coupled in the IMS
200 or to an optical test bench (410, FIG. 4) in an optical test
subsystem (400, FIG.4). In addition, the controller 157 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the high angle collecting FRU 240, the controllers (157, 195) can
be programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, the polarizers 156 and the third set of highly reflective
curved surfaces (158 and 159), the chamber 241, the input optical
connection devices 242a, and the output optical connection devices
242b can be adjusted to reduce or eliminate the adjustment of the
other components of the IMS 200 and the need to re-calibrate the
IMS 200.
[0111] The high angle collecting FRU 240 can be coupled to the
wafer-positioning FRU 290 using the optically transparent windows.
In other embodiments, the high angle collecting FRU 240 can be
coupled to the wafer-positioning FRU 290 using one or more optical
fibers. For example, one or more high angle diffracted beams 98 can
be reflected from the measurement spot on a wafer in the
wafer-positioning FRU 290 to high angle collecting FRU 240 when the
IMS 200 is operating in a first mode (HIGH). In addition, the high
angle diffracted beam 98 can have a reflection angle that can be
between approximately 15 degrees and approximately 50 degrees from
a normal vector perpendicular to the wafer surface. Alternatively,
the high angle collecting FRU 240 can include one or more movable
mirrors.
[0112] When the second beam reflection FRU 245 is installed in the
IMS 200, the second beam reflection FRU 245 can receive one or more
high angle collection beams 151a from the high angle collecting FRU
240 and can provide one or more high angle reflected beams 151b to
the second beam selector FRU 255. One or more of the beams (151a
and 151b) can include one or more reference beams and/or one or
more measurement beams. When pre-calibrated and/or pre-aligned FRUs
(240, 245) are used, pre-calibrated and/or pre-aligned beams (151a,
151b) can be established.
[0113] The second beam reflection FRU 245 can comprise a chamber
246, one or more input optical connection devices 247a, one or more
output optical connection devices 247b, a controller 154, and one
or more attachment elements 248 for coupling the second beam
reflection FRU 245 to the compact chassis assembly 201.
Alternatively, additional subsystems may be included.
[0114] The second beam reflection FRU 245 can include one or more
third low-loss reflecting surfaces 150a that can be used to direct
the high angle collection beam 151a to the output optical
connection devices 247b when the metrology system is operating in
the first mode (HIGH). One or more of the third low-loss reflecting
surfaces 150a can be a first surface convex mirror, or a concave
fused silica mirror. The third low-loss reflecting surfaces 150a
can be used to correct aberrations so that the high angle reflected
beam 151b has near diffraction-limited quality from 190 nm to 1100
nm. In addition, additional components (not shown) can be included
that can perform positioning, reflecting, summing, and/or focusing
functions as required.
[0115] When the second beam reflection FRU 245 is being constructed
and/or repaired, the third low-loss reflecting surfaces 150a can be
aligned and mounted within the chamber 246; the input optical
connection devices 247a and the output optical connection devices
247b can be aligned and mounted in one or more of the chamber
walls; and the chamber 246 can be evacuated and sealed.
[0116] When a failure has occurred in a calibrated second beam
reflection FRU 245 in the IMS 200, the failed second beam
reflection FRU can be replaced by a replacement second beam
reflection FRU that has been pre-calibrated and/or pre-aligned. The
characterization parameters associated with the failed and/or
replacement second beam reflection FRU 245 can include the expected
and/or actual lifetimes, the expected and/or actual
repair/replacement times, the expected and/or actual
calibration/measurement times, the expected and/or actual
wavelength data, the expected and/or actual intensity data, the
expected and/or actual beam width data, the expected and/or actual
temperature data, the expected and/or actual adjustment ranges, the
expected and/or actual polarization values, or the expected and/or
actual loss data, or any combination thereof for the third low-loss
reflecting surfaces 150a, the chamber 246, the input optical
connection devices 247a, the output optical connection devices
247b, and the optical fiber 244, or other components in the second
beam reflection FRU 245.
[0117] One or more of the controllers (154, 195) can be used for
storing characterization parameters and operational data for the
second beam reflection FRU 245 and/or for executing operational and
calibration procedures using the characterization parameters for
the second beam reflection FRU 245. The controllers (154, 195) can
also be used to control the calibrated second beam reflection FRU
245 when the second beam reflection FRU 245 is coupled in the IMS
200 or to an optical test bench (410, FIG. 4) in an optical test
subsystem (400, FIG.4). In addition, the controller 154 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the second beam reflection FRU 245, the controllers (154, 195) can
be programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, the third low-loss reflecting surfaces 150a, the chamber
246, the input optical connection devices 247a, and the output
optical connection devices 247b, the optical fiber 244 can be
adjusted to reduce or eliminate the adjustment of the other
components of the IMS 200 and the need to re-calibrate the IMS
200.
[0118] The second beam reflection FRU 245 can be coupled to the
second beam selector FRU 255 using the optical connection devices
(247b and 257a) and one or more optical fibers 249. In other
embodiments, the second beam reflection FRU 245 can be coupled to
the second beam selector FRU 255 using one or more optically
transparent windows when the optical connection devices (247b and
257a) include optically transparent windows. For example, one or
more high angle reflected beams 151 b can be sent from the second
beam reflection FRU 245 to the second beam selector FRU 255 when
the IMS 200 is operating in a first mode (HIGH).
[0119] When the low angle collecting FRU 250 is installed in the
IMS 200, the low angle collecting FRU 250 can receive one or more
input beams 165a from the wafer-positioning FRU 290 and can provide
one or more low angle output beams 165b to the second beam selector
FRU 255. One or more of the beams (165a and 165b) can include one
or more reference beams and/or one or more measurement beams. When
pre-calibrated and/or pre-aligned FRUs (250, 290) are used,
pre-calibrated and/or pre-aligned beams (165a, 165b) can be
established.
[0120] The low angle collecting FRU 250 can comprise a chamber 251,
one or more input optical connection devices 252a, one or more
output optical connection devices 252b, one or more attachment
elements 253 for coupling the low angle collecting FRU 250 to one
or more walls of the wafer-positioning chamber 291, and a
controller 167. In various examples, the input optical connection
devices (222a, 232a, 242a, and 252a) and the output optical
connection devices (222b, 232b, 242b, and 252b) can include optical
windows, optical fibers, and/or other optical devices that can be
optically transparent in ranges from approximately 150 nm to
approximately 1000 nm.
[0121] The low angle collecting FRU 250 can include one or more
polarizers 166 that can linearly polarize the light after the beam
is reflected from the wafer 101, and the polarization can be
selected to maximize the sensitivity of the optical measurement to
the parameters of the sample. In some examples, one or more of the
polarizers 166 can provide the S-polarized light. In other
examples, a polarizer 166 may be rotated to collect additional
measurement data. In addition, a fourth set of highly reflective
curved surfaces (168 and 169) can be used to fold the light path so
that the non-normal incidence angles do not lead to unnecessarily
large footprint for the low angle collecting FRU 250. The small
footprint allows the low angle collecting FRU 250 to be used in a
compact IMS 200 with other small FRUs. One or more of the fourth
set of highly reflective curved surfaces (168 and 169) can be a
first surface convex mirror, or a concave fused silica mirror. The
highly reflective surfaces can be used to correct aberrations so
that the low angle output beam 165b has near diffraction-limited
quality from 190 nm to 1100 nm. In addition, additional components
(not shown) can be included that can perform positioning,
reflecting, summing, and/or focusing functions as required.
[0122] In some embodiments, the low angle collecting FRU 250 can
receive one or more low angle diffracted beams 99 from the wafer
surface as a low-angle input beam 165a, and the light reflected
from the wafer (input beam 165a) can be collected and imaged the
fourth set of highly reflective curved surfaces (168 and 169). For
example, the low-angle input beam 165a can include one or more
reference beams and/or one or more measurement beams from the wafer
surface
[0123] In addition, the polarizer 166 may be configured to have
beam-splitting properties and can be made from alpha barium borate.
For example, a beam may be split into S-polarized light, and
P-polarized light. Some of the optical fibers used in the metrology
system can have smaller core diameters than other fibers so that
the measurements are not overly sensitive to focus. In various
configurations, the diameter of optical fibers or optical windows
can be used to determine the geometric size of the measurement spot
on the wafer 101. A preventive maintenance procedure for the low
angle collecting FRU 250 can be scheduled and can be based on the
expected lifetime for a polarizer 166, the fourth set of highly
reflective curved surfaces (168 and 169), and/or another
component.
[0124] When the low angle collecting FRU 250 is constructed and/or
repaired, the polarizers 166 and the fourth set of highly
reflective curved surfaces (168 and 169) can be aligned and mounted
within the chamber 261; the input optical connection devices 252a
and the output optical connection devices 252b can be mounted and
aligned in one or more of the chamber walls; and the chamber 261
can be evacuated and sealed.
[0125] When a failure has occurred in a calibrated low angle
collecting FRU 250 in the IMS 200, the failed low angle collecting
FRU can be replaced by a replacement low angle collecting FRU that
has been pre-calibrated and/or pre-aligned. The characterization
parameters associated with the failed and/or replacement low angle
collecting FRU 250 can include the expected and/or actual
lifetimes, the expected and/or actual repair/replacement times, the
expected and/or actual calibration/measurement times, the expected
and/or actual wavelength data, the expected and/or actual intensity
data, the expected and/or actual beam width data, the expected
and/or actual temperature data, the expected and/or actual
adjustment ranges, the expected and/or actual polarization values,
or the expected and/or actual loss data, or any combination thereof
for the polarizers 166 and the fourth set of highly reflective
curved surfaces (168 and 169), the chamber 251, the input optical
connection devices 252a, and the output optical connection devices
252b, or other components in the low angle collecting FRU 250.
[0126] One or more of the controllers (167, 195) can be used for
storing characterization parameters and operational data for the
low angle collecting FRU 250 and/or for executing operational and
calibration procedures using the characterization parameters for
the low angle collecting FRU 250. The controllers (167,195) can
also be used to control the calibrated low angle collecting FRU 250
when the low angle collecting FRU 250 is coupled in the IMS 200 or
to an optical test bench (410, FIG. 4) in an optical test subsystem
(400, FIG.4). In addition, the controller 167 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the low angle collecting FRU 250, the controllers (167, 195) can be
programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, the polarizers 166 and the fourth set of highly reflective
curved surfaces (168 and 169), the chamber 251, the input optical
connection devices 252a, and the output optical connection devices
252b can be adjusted to reduce or eliminate the adjustment of the
other components of the IMS 200 and the need to re-calibrate the
IMS 200.
[0127] The low angle collecting FRU 250 can be coupled to the
wafer-positioning FRU 290 using the optically transparent windows.
In other embodiments, the low angle collecting FRU 250 can be
coupled to the wafer-positioning FRU 290 using one or more optical
fibers. When two or more optically transparent windows are used,
they must also be matched and aligned properly. For example, one or
more low angle diffracted beams 99 can be sent from the measurement
spot on a wafer in the wafer-positioning FRU 290 to the low angle
collecting FRU 250 when the IMS 200 is operating in the second mode
(LOW). In addition, the low angle diffracted beam 99 can have a
reflection angle that can be between approximately 40 degrees and
approximately 70 degrees from a normal vector perpendicular to the
wafer surface. Alternatively, the low angle collecting FRU 250 can
include one or more movable mirrors.
[0128] When the second beam selector FRUs 255 is installed in the
IMS 200, the second beam selector FRUs 255 can receive one or more
first input beams 161a from the second beam reflection FRU 245, can
receive one or more second input beams 162a from low angle
collecting FRU 250, and can provide one or more output beams 163a
to the analyzer FRU 260. One or more of the beams (161a, 162a, and
163a) can include one or more reference beams and/or one or more
measurement beams. When pre-calibrated and/or pre-aligned FRUs
(245, 255) are used, pre-calibrated and/or pre-aligned beams (162a,
163a) can be established.
[0129] The second beam selector FRU 255 can comprise a chamber 256,
one or more first input optical connection devices 257a, one or
more second input optical connection devices 257b, one or more
output optical connection devices 257c, a controller 164, and one
or more attachment elements 258 for coupling the second beam
selector FRU 255 to the compact chassis assembly 201.
[0130] The second beam selector FRU 255 can comprise one or more
fourth low-loss reflecting surfaces 160a that can be used to allow
the first input beam 161a to pass through to the output optical
connection devices 257c when the metrology system is operating in
the first mode (HIGH) and that can be used to direct the second
input beam 162a to the output optical connection devices 257c when
the metrology system is operating in the second mode (LOW) One or
more of the fourth low-loss reflecting surfaces 160a can be a first
surface convex mirror, or a concave fused silica mirror. The fourth
low-loss reflecting surfaces 160a can be used to correct
aberrations introduced so that the output beam 163a has near
diffraction-limited quality from 190 nm to 1100 nm. For example,
one or more of the fourth low-loss reflecting surfaces 160a can be
moved to a first position when the IMS 200 is operating in the
first mode (HIGH), and one or more of the fourth low-loss
reflecting surfaces 160a can be moved to a second position when the
IMS 200 is operating in the second mode (LOW). In addition,
additional components (not shown) can be included that can perform
positioning, reflecting, summing, and/or focusing functions as
required.
[0131] When the second beam selector FRU 255 is constructed and/or
repaired, the fourth low-loss reflecting surfaces 160a can be
aligned and mounted within the chamber 256; the first input optical
connection devices 257a, the second input optical connection
devices 257b and the output optical connection devices 257c can be
mounted in one or more of the chamber walls; and the chamber 256
can be evacuated and sealed.
[0132] When a failure has occurred in a calibrated second beam
selector FRU 255 in the IMS 200, the failed second beam selector
FRU 255 can be replaced by a replacement second beam selector FRU
that has been pre-calibrated and/or pre-aligned. The
characterization parameters associated with the failed and/or
replacement second beam selector FRU 255 can include the expected
and/or actual lifetimes, the expected and/or actual
repair/replacement times, the expected and/or actual
calibration/measurement times, the expected and/or actual
wavelength data, the expected and/or actual intensity data, the
expected and/or actual beam width data, the expected and/or actual
temperature data, the expected and/or actual adjustment ranges, the
expected and/or actual polarization values, or the expected and/or
actual loss data, or any combination thereof for the fourth
low-loss reflecting surfaces 160a, the chamber 256, the input
optical connection devices (257a, 257b), the output optical
connection devices 257c, and the optical fibers (249, 254), or
other components in the second beam selector FRU 255.
[0133] One or more of the controllers (164, 195) can be used for
storing characterization parameters and operational data for the
second beam selector FRU 255 and/or for executing operational and
calibration procedures using the characterization parameters for
the second beam selector FRU 255. The controllers (164, 195) can
also be used to control the calibrated second beam selector FRU 255
when the second beam selector FRU 255 is coupled in the IMS 200 or
to an optical test bench (410, FIG. 4) in an optical test subsystem
(400, FIG.4). In addition, the controller 164 can perform
monitoring procedures that can be used to provide warning data or
failure data that can be used to initiate a replacement procedure
during operating or calibrating procedures. When a new FRU is
installed in the IMS 200 or when a new component is installed in
the second beam selector FRU 255, the controllers (164, 195) can be
programmed to compensate for the system level variations, and a
system level maintenance procedure may not be required. For
example, fourth low-loss reflecting surfaces 160a, the chamber 256,
the input optical connection devices (257a, 257b), the output
optical connection devices 257c, and the optical fibers (249, 254)
can be adjusted to reduce or eliminate the adjustment of the other
components of the IMS 200 and the need to re-calibrate the IMS
200.
[0134] In some system configurations, the second beam selector FRU
255 can be coupled to the analyzer FRU 260 using the optical
connection devices (257c and 262a) and one or more optical fibers
259. In other configurations, one or more optically transparent
windows can be used when the optical connection devices (257c and
262a) include optically transparent windows.
[0135] When the analyzer FRU 260 is installed in the IMS 200, the
analyzer FRU 260 can receive one or more first input beams 171a
from the second beam selector FRU 255 and can provide one or more
output beams 172a to the measurement FRU 265. When pre-calibrated
and/or pre-aligned FRUs (255, 260) are used, pre-calibrated and/or
pre-aligned beams (171a, 172a) can be established.
[0136] The analyzer FRU 260 can comprise a chamber 261, one or more
first input optical connection devices 262a, one or more output
optical connection devices 262b, and one or more attachment
elements 263 for coupling the analyzer FRU 260 to the compact
chassis assembly 201. In addition, the analyzer FRU 260 can
comprise one or more analyzer subsystems 170, and a controller 174.
For example, the analyzer FRU 260 can include one or more highly
accurate beam analyzers. Alternatively, additional subsystems
and/or components may be included. In some examples, the analyzer
FRU 260 can comprise one or more multi-channel spectrometers that
can measure the spectrum in several beams simultaneously. In
addition, the analyzer FRU 260 can comprise multiple linear
detector arrays or one or more two dimensional detector arrays.
[0137] When the IMS 200 is operating in the first mode "HIGH", one
or more of the high-angle outputs from the wafer can be directed to
the analyzer FRU 260 using the high angle collection FRU 240, the
second beam reflection FRU 245, and the second beam selector FRU
255. When the IMS 200 is operating in the first mode "HIGH", a high
angle of incidence can be used for one or more of the incident
beams and one or more of the reflected beams. When the IMS 200 is
operating in the second mode "LOW", one or more of the low-angle
outputs from the wafer can be directed to the analyzer FRU 260
using the low angle collection FRU 250 and the second beam selector
FRU 255. When the IMS 200 is operating in the second mode "LOW", a
low angle of incidence can be used for one or more of the incident
beams and one or more of the reflected beams.
[0138] The analyzer FRU 260 can analyze one or more reference beams
and/or one or more measurement beams from the surface of the wafer.
The analyzer FRU 260 can include reflecting, summing, selecting,
and/or analyzing components that are configured to operate over a
wide range of wavelengths. A preventive maintenance procedure for
the analyzer FRU 260 can be scheduled and may be based on a
lifetime for a measurement device or a lamp lifetime. When a new
measurement device is installed in the analyzer FRU 260, the
controller 174 can be programmed to compensate for the variations
caused by the new measurement device. In addition, if a new lamp is
installed in the source FRU 205 associated with the analyzer FRU
260, the controller 174 can be programmed to compensate for the
lamp-to-lamp variations. When one or more of the other components
in the analyzer FRU 260 are replaced and/or adjusted, the
controller 174 can be programmed to compensate for the replaced
part and to perform adjustments as required.
[0139] When a failure has occurred in a calibrated analyzer FRU 260
in the IMS 200, the failed analyzer FRU can be replaced by a
replacement analyzer FRU that has been pre-calibrated and/or
pre-aligned. The characterization parameters associated with the
failed and/or replacement analyzer FRU 260 can include the expected
and/or actual lifetimes, the expected and/or actual
repair/replacement times, the expected and/or actual
calibration/measurement times, the expected and/or actual
wavelength data, the expected and/or actual intensity data, the
expected and/or actual beam width data, the expected and/or actual
temperature data, the expected and/or actual adjustment ranges, the
expected and/or actual polarization values, or the expected and/or
actual loss data, or any combination thereof for the reflecting,
summing, selecting, and/or analyzing components, the chamber 261,
the input optical connection devices 262a, and the output optical
connection devices 262s, the optical fibers (259, 264), or other
components in the analyzer FRU 260.
[0140] The analyzer FRU 260 can be coupled to the measurement FRU
265 using the optical connection devices (262b and 267a) and one or
more optical fibers 264. Alternatively, the analyzer FRU 260 can be
coupled to the measurement FRU 265 using one or more optically
transparent windows when the optical connection devices (262b and
267a) include optically transparent windows.
[0141] In alternate embodiments, the analyzer FRU 260 and
measurement FRU 265 may be combined into a single FRU.
[0142] When the measurement FRU 265 is installed in the IMS 200,
the measurement FRU 265 can receive one or more optical signals 178
from the analyzer FRU 260 and can provide data to the controller
FRU 280.
[0143] The measurement FRU 265 can comprise a chamber 266, one or
more input optical connection devices 267a mounted in a wall of the
chamber 261, and one or more attachment elements 268 for coupling
the measurement FRU 265 to the compact chassis assembly 201.
[0144] The measurement FRU 265 can comprise one or more detection
subsystems 175, one or more databases 176, and one or more
controllers 177. When the IMS 200 is operating in the first mode
"HIGH", high incident angle data from the wafer 101 can be measured
using the measurement FRU 265, and when the IMS 200 is operating in
the second mode "LOW", low incident angle data from the wafer 101
can be measured using the measurement FRU 265. The measurement FRU
265 can comprise one or more spectrometers. For example, the
spectrometers can operate from the Deep-Ultra-Violet to the visible
regions of the spectrum.
[0145] The measurement FRU 265 can measure one or more reference
beams and/or one or more measurement beams from the surface of the
wafer. The measurement FRU 265 can include measuring, sensing,
reflecting, summing, and/or selecting components that are
configured to operate over a wide range of wavelengths.
[0146] When the measurement FRU 265 is used in the IMS 200, a
preventive maintenance procedure for the measurement FRU 265 can be
scheduled and may be based on a reference source lifetime or a
measurement device lifetime. When a new FRU is installed in the IMS
200, the controller 177 can be programmed to compensate for the
variations caused by the new FRU. In addition, if a new lamp is
installed in the source FRU 205 associated with the analyzer FRU
260, the controller 177 can be programmed to compensate for the
lamp-to-lamp variations. When one or more of the other components
in the measurement FRU 265 are replaced and/or adjusted, the
controller 177 can be programmed to compensate for the replaced
part and to perform adjustments as required.
[0147] The measurement FRU 265 can use the measured data to
determine the parameters of the target structure on the wafer at
the measurement spot. The parameters can be the thicknesses of
films, line width critical dimension (CD), the sidewall slope of
lines, etc, and the data can be converted into spectral, absolute,
polarized reflectance and compared to the spectrum library to find
the best match and therefore the unknown structure parameters.
There are many alternative approaches to process the measured data
to yield structure parameters.
[0148] The camera FRU 270 can comprise a chamber 271, one or more
output optical connection devices 272 mounted in a wall of the
chamber 271, and one or more attachment elements 273 for coupling
the camera FRU 270 to the compact chassis assembly 201. The camera
FRU 270 can include one or more camera subsystems 180 and one or
more controllers 186 that can be used to inspect and/or align the
wafer 101.
[0149] The camera FRU 270 can receive one or more reference beams,
one or more inspection beams, and/or one or more alignment beams
from the surface of the wafer. The camera FRU 270 can include
measuring, sensing, reflecting, summing, and/or selecting
components that are configured to be compatible with light sources
operating in the visible region or outside the visible region. When
the camera FRU 270 is used in an IM system, a preventive
maintenance procedure for the camera FRU 270 can be scheduled and
may be based on a source lifetime or a sensing device lifetime.
When a new FRU is installed in the IMS 200, the controller 186 can
be programmed to compensate for the variations caused by the new
FRU. In addition, when one or more of the components in the camera
FRU 270 are replaced and/or adjusted, the controller 186 can be
programmed to compensate for the replaced part and to perform
adjustments as required.
[0150] The imaging FRU 275 can comprise a chamber 276, one or more
input optical connection devices 277a mounted in a wall of the
chamber 276, one or more output optical connection devices 277b
mounted in a wall of the chamber 276, and one or more attachment
elements 278 for coupling the imaging FRU 275 to the compact
chassis assembly 201.
[0151] The imaging FRU 275 can comprise one or more one illuminator
subsystems 184, one or more of the imaging subsystems 185, and one
or more controllers 187. For example, one or more of the
illuminator subsystems 184 can be coupled to one or more of the
imaging subsystems 185 and can provide one or more sources of light
having both visible and non-visible wavelengths.
[0152] The imaging FRU 275 can be coupled to the camera FRU 270
using the optical connection devices (272 and 277a) and one or more
optical fibers 274. Alternatively, the imaging FRU 275 can be
coupled to the camera FRU 270 using one or more optically
transparent windows when the optical connection devices (272 and
277a) include optically transparent windows.
[0153] The imaging FRU 275 can be coupled to the wafer-positioning
FRU 290 using the optical connection devices (277b and 94) and one
or more optical fibers 284. Alternatively, imaging FRU 275 can be
coupled to the wafer-positioning FRU 290 using one or more
optically transparent windows when the optical connection devices
(277b and 94) include optically transparent windows. For example,
the imaging FRU 275 can be mounted next to and/or attached to the
wafer-positioning chamber 291.
[0154] The imaging FRU 275 can include sourcing, measuring,
sensing, reflecting, summing, and/or selecting components that are
configured to operate over a wide range of wavelengths. When the
measurement FRU 265 is used in the IMS 200, a preventive
maintenance procedure for the measurement FRU 265 can be scheduled
and may be based on a reference source lifetime or a measurement
device lifetime. When a new FRU is installed in the IMS 200, the
controller 177 can be programmed to compensate for the variations
caused by the new FRU. In addition, if a new lamp is installed in
the source FRU 205 associated with the analyzer FRU 260, the
controller 177 can be programmed to compensate for the lamp-to-lamp
variations. When one or more of the components in the measurement
FRU 265 are replaced and/or adjusted, the controller 177 can be
programmed to compensate for the replaced part and to perform
adjustments as required.
[0155] The controller FRU 280 can comprise a chamber 281 and one or
more attachment elements 283 for coupling the controller FRU 280 to
the compact chassis assembly 201.
[0156] The controller FRU 280 can comprise one or more controllers
195 and one or more interface elements (not shown) that can be used
to couple the IMS 200 to other systems in a factory environment. In
some examples, controller 195 may be configured to use factory
level intervention and/or judgment rules to determine which
processes are monitored and which data can be used. In addition,
factory level intervention and/or judgment rules can be used to
determine how to manage the data when a process can be changed,
paused, and/or stopped. In addition, controller 195 can provide
configuration information and update information.
[0157] The auto-focusing FRU 285 can comprise a chamber 286, one or
more optical connection devices 287 mounted in a wall of the
chamber 286, and one or more attachment elements 288 for coupling
the auto-focusing FRU 285 to the compact chassis assembly 201.
[0158] The auto-focusing FRU 285 can comprise one or more
auto-focusing subsystems 190, and one or more controllers 194. For
example, autofocus can be performed by scanning the measurement
optics in the Z-direction and moving to the Z position that
maximizes signal.
[0159] The auto-focusing FRU 285 can be coupled to the
wafer-positioning FRU 290 using the optical connection devices (287
and 95) and one or more optical fibers 289. Alternatively, the
auto-focusing FRU 285 can be coupled to the wafer-positioning FRU
290 using one or more optically transparent windows when the
optical connection devices (287 and 95) include optically
transparent windows. For example, the auto-focusing FRU 285 can be
mounted next to and/or attached to the wafer-positioning chamber
291. Alternatively, other focusing techniques may be used.
[0160] When a failure occurs or when the performance degrades, one
or more of the FRUs (205, 210, 215, 220, 225, 230, 235, 240, 245,
250, 255, 260, 265, 270, 275, 280, 285, and 290) can be replaced
with a new unit. In some examples, a new FRU (205, 210, 215, 220,
225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285,
and 290) can be obtained from a storage facility that can be
located near-by, and the amount of down time can be minimized. In
other examples, the failed FRU can be repaired and replaced in a
short amount of time. When a new FRU is installed in the IMS 200,
one or more of the other FRUs can be adjusted. In addition, when a
new optical source is installed in the IMS 200, one or more of the
FRUs (205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260,
265, 270, 275, 280, 285, and 290) can be adjusted.
[0161] The attachment elements (208, 213, 218, 223, 228, 233, 238,
243, 248, 253, 258, 263, 268, 273, 278, 283, 288, and 293) can have
thermal conductive properties, thermal isolation properties,
mechanical properties, electrical properties, and/or
vibration-reduction properties as required. For example, the
attachment elements (208, 213, 218, 223, 228, 233, 238, 243, 248,
253, 258, 263, 268, 273, 278, 283, 288, and 293) can be configured
to allow the FRUs (205, 210, 215, 220, 225, 230, 235, 240, 245,
250, 255, 260, 265, 270, 275, 280, 285, and 290) to be quickly and
precisely coupled to and/or decoupled from the chamber wall and
from one or more optical test benches (410, FIG. 4)used for testing
and/or aligning. For example, when a FRU requires maintenance, it
can be quickly and easily removed from the IMS 200 and can be
tested using an optical test subsystem (400, FIG. 4).
[0162] One or more of the FRUs (205, 210, 215, 220, 225, 230, 235,
240, 245, 250, 255, 260, 265, 270, 275, 280, 285, and 290) can be
used when performing real-time or non-real-time procedures. One or
more of the controllers (107, 117, 124, 134, 137, 144, 147, 154,
157, 164, 167, 174, 177, 184, 187, 194, 195, and 197) can receive
real-time or non-real-time data to update subsystem, processing
element, process, recipe, profile, image, pattern, and/or model
data. One or more of the controllers (107, 117, 124, 134, 137, 144,
147, 154, 157, 164, 167, 174, 177, 184, 187, 194, 195, and 197) can
be coupled to one or more controllers 195 in a controller FRU 280
and can exchange data using one or more Semiconductor Equipment
Communications Standard (SECS) messages, can read and/or remove
information, can feed forward, and/or can feedback the information,
and/or can send information as a SECS message.
[0163] Those skilled in the art will recognize that the controllers
(107, 117, 124, 134, 137, 144, 147, 154, 157, 164, 167, 174, 177,
184, 187, 194, 195, and 197) can include hardware, firmware, and
software (not shown) as required.
[0164] The controllers (107, 117, 124, 134, 137, 144, 147, 154,
157, 164, 167, 174, 177, 184, 187, 194, 195, and 197) can be used
to control FRU operation when the FRU in installed in the IMS 200
or the optical test subsystem (400, FIG. 4).
[0165] In some examples, the controllers (107, 117, 124, 134, 137,
144, 147, 154, 157, 164, 167, 174, 177, 184, 187, 194, 195, and
197) can be used to turn-on or turn-off one or more components; can
be used to turn-on or turn-off one or more of the optical beams;
and can be used to determine the number of optical beams and one or
more beam properties such as beam width and beam angle.
[0166] When two or more optical fibers are used, they must be
matched and/or aligned properly, and the controllers (107, 117,
124, 134, 137, 144, 147, 154, 157, 164, 167, 174, 177, 184, 187,
194, 195, and 197) can be programmed to perform the aligning and/or
matching procedures. In addition, when two or more optically
transparent windows are used, they must be matched and/or aligned
properly, the controllers (107, 117, 124, 134, 137, 144, 147, 154,
157, 164, 167, 174, 177, 184, 187, 194, 195, and 197) can be
programmed to perform the aligning and/or matching procedures.
[0167] In still other configurations, some of the FRUs (205, 210,
215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275,
280, 285, and 290) can include some primary components to be used
during operation and some secondary components that can be used to
pre-align the FRU before installation. The secondary components can
include positioning devices, light-collection optics, one or more
shutters, and one or more filters. For example, the secondary
components can be used to provide operational data. In addition,
the inclusion of the secondary components in the FRUs can improve
the reliability of the IMS 200 since the secondary components have
a longer lifetime than the primary component of the system. For
example, the primary components can have a more harmful working
environment that can include high temperatures, constant motion,
and exposure to DUV light. During a FRU maintenance procedure, the
secondary components of the FRU can be inspected and re-conditioned
under an off-line inspection and repair station for next
maintenance. The reliability of the IMS 200 is improved
significantly. Pre-aligning the key components in the FRU can also
significantly reduce or eliminate the need of adjusting the other
components or re-calibrating the system when the FRU is
swapped.
[0168] In some embodiments, the IMS 200 can include Optical Digital
Profilometry (ODP) elements (not shown), and ODP elements/systems
are available from Timbre Technologies Inc. (a TEL company).
Alternatively, other metrology data-extraction systems may be
used.
[0169] The IMS 200 can use polarizing reflectometry, spectroscopic
ellipsometry, spectroscopic reflectometry, or other optical
measurement techniques to measure accurate device profiles,
accurate CDs, and multiple layer film thickness of a wafer. The
integrated metrology process (iODP) can be executed as an
integrated process in an integrated group of subsystems. In
addition, the integrated process eliminates the need to break the
wafer for performing the analyses or waiting for long periods for
data from external systems. iODP techniques can be used with the
existing thin film metrology systems for inline profile and
critical dimension (CD) measurement, and can be integrated with TEL
processing systems and/or lithography systems to provide real-time
process monitoring and control.
[0170] Data from the IMS 200 can include measured, predicted,
and/or simulated data associated with the FRUs (205, 210, 215, 220,
225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285,
and 290), and the data can be stored using processing, wafer, lot,
recipe, site, or wafer location data. The data can include
variables associated with the metrology devices, and metrology
device models used in the various FRUs.
[0171] The IMS 200 can make measurements at two azimuth angles 180
degrees apart, and this technique can be used to reduce the
sensitivity of the measurements to wafer tilt and other asymmetries
in the optical system. The FRUs described herein can be used with
other types of metrology systems.
[0172] FIG. 3 illustrates an exemplary flow diagram for a procedure
for using an Integrated Metrology Sensor (IMS) in accordance with
embodiments of the invention.
[0173] In 310, an error message can be received by a controller 195
in the IMS 200. Alternatively, the error message can be received by
another controller. In some examples, the error message can
identify a malfunctioning FRU. In other example, the IMS can detect
an error condition by comparing an operating data to acceptable
ranges and determining when the operating data (measurement) is
outside the acceptable range.
[0174] In 320, a malfunctioning FRU can be identified, and a
correction (repair) procedure can be established. In some examples,
one or more tuning or alignment steps can be performed while the
FRU is still installed in the IMS 200.
[0175] In 330, a query can be performed to determine if the
identified error condition has been removed. When the identified
error condition has been removed, procedure 300 can branch to step
350 and procedure 300 can continue as shown in FIG. 3. When the
identified condition has not been removed, procedure 300 can branch
to step 340 and procedure 300 can continue as shown in FIG. 3. the
identified malfunctioning FRU can be replaced if the error
condition cannot be eliminated.
[0176] In 340, the malfunctioning FRU can be replaced with a
pre-aligned replacement FRU.
[0177] In 350, a query can be performed to determine if additional
error conditions exist in the IMS. When additional error conditions
exist, procedure 300 can branch to 320, and when the error
conditions have been eliminated procedure 300 can branch to
360.
[0178] In 360, the repaired IMS can be used to measure wafers.
[0179] FIG. 5 illustrates an exemplary flow diagram for a procedure
for creating a calibrated FRU for use in an Integrated Metrology
Sensor (IMS) in accordance with embodiments of the invention.
[0180] In 510, a first set of initial components can be selected
based on an expected replacement time for the FRU when an FRU is
initially designed.
[0181] In 520, a required replacement time can be determined.
During the initial design procedures, the first set of initial
components can be obtained, a FRU can be assembled, the FRU can be
calibrated, the calibrated FRU can be installed, and the time
required for these procedures can be established.
[0182] In 530, a query can be performed to determine if the
determined required time is less than the expected replacement time
for the FRU. When the required time is less than the replacement
time, procedure 500 can branch to 540. When the required time is
not less than the replacement time, procedure 500 can branch to
550.
[0183] In 540, the first set of initial components (initial design)
can be established as a potential design solution.
[0184] In 550, one or more corrective actions can be performed. The
corrective actions can include selecting a component from a
different vendor, selecting a component with a faster assembly
time, selecting a component with a faster calibration time,
selecting a component with a shorter repair time, or selecting a
component with a longer expected lifetime, or any combination
thereof.
[0185] In some embodiments, operating an Integrated Metrology
Sensor (IMS) can include: mounting a plurality of calibrated Field
Replaceable Units (FRUs) using a plurality of pre-aligned mounting
devices at pre-determined locations on the compact chassis
assembly; positioning a wafer in a calibrated wafer-positioning FRU
removably coupled to the compact chassis assembly and configured
for supporting and aligning a wafer; providing one or more
pre-aligned high-angle incident beams to a target on the wafer
using a first set of calibrated FRUs, the first set of calibrated
FRUs being removably coupled to the compact chassis assembly;
receiving at least one pre-aligned high-angle diffracted beam from
the target on the wafer using a second set of calibrated FRUs, the
second set of calibrated FRUs being removably coupled to the
compact chassis assembly; performing a first corrective action when
a first error condition exists in one of the first set of
calibrated FRUs, or in one of the second set of calibrated FRUs, or
any combination thereof; and identifying the target using the at
least one pre-aligned high-angle diffracted beam when the first
error condition does not exist.
[0186] In addition, the first correction action can include tuning
one or more of the calibrated FRUs, aligning one or more of the
calibrated FRUs, repairing one or more of the calibrated FRUs, or
replacing one or more of the calibrated FRUs with a pre-aligned
replacement FRU, or any combination thereof.
[0187] In other embodiments, the operating method can further
include: providing one or more pre-aligned low-angle incident beams
to the target on the wafer using a third set of calibrated FRUs,
the third set of calibrated FRUs being removably coupled to the
compact chassis assembly; receiving at least one pre-aligned
low-angle diffracted beam from the target on the wafer using a
fourth set of calibrated FRUs, the fourth set of calibrated FRUs
being removably coupled to the compact chassis assembly; performing
a second corrective action when a second error condition exists in
one of the third set of calibrated FRUs, or in one of the fourth
set of calibrated FRUs, or any combination thereof; and identifying
the target using the at least one pre-aligned low-angle diffracted
beam when the second error condition does not exist.
[0188] FIG. 4 illustrates a simplified block diagram of a test
subsystem in accordance with embodiments of the invention. In the
illustrated embodiment, an optical test subsystem 400 is shown that
includes an optical test bench 410, one or more optical test
sources 420, one or more optical measurement tools, and a test
controller 490. Alternately, other configurations may be used.
[0189] The test controller 490 can be coupled to the one or more
optical test sources 420, to the FRU being tested, and to the one
or more optical measurement tools. For example, the test controller
can include test procedures for each of the FRUs (205, 210, 215,
220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280,
285, and 290). In some cases, one or more "golden" FRUs can be used
to verify test and/or operational procedures.
[0190] In some examples, when alignment or testing is required, the
second beam reflection FRU 245 can be aligned and/or tested in the
IMS 200. In other examples, the second beam reflection FRU 245 can
be easily removed from the IMS 200 and attached to the optical test
bench (410, FIG. 4) in an optical test subsystem (400, FIG.4) using
attachment elements 243. During alignment or testing, one or more
optical test sources (420, FIG. 4) can be coupled to one or more of
the input optical connection devices 247a, and one or more
measurement devices (430, FIG. 4) can be coupled to one or more of
the output optical connection devices 247b. During alignment and/or
testing, the characterization parameters of the second beam
reflection FRU 245 can be tested and/or established using the
optical test subsystem (400, FIG. 4). When the second beam
reflection FRU 245 is being aligned and/or tested, one or more sets
of characterization parameters can be used and/or updated.
[0191] Although only certain embodiments of this invention have
been described in detail above, those skilled in the art will
readily appreciate that many modifications are possible in the
embodiments without materially departing from the novel teachings
and advantages of this invention. Accordingly, all such
modifications are intended to be included within the scope of this
invention.
[0192] Thus, the description is not intended to limit the invention
and the configuration, operation, and behavior of the present
invention has been described with the understanding that
modifications and variations of the embodiments are possible, given
the level of detail present herein. Accordingly, the preceding
detailed description is not mean or intended to, in any way, limit
the invention--rather the scope of the invention is defined by the
appended claims.
* * * * *